diff --git a/src/locale/ar.js b/src/locale/ar.js
--- a/src/locale/ar.js
+++ b/src/locale/ar.js
@@ -16,15 +16,15 @@ const locale = {
     past: 'منذ %s',
     s: 'ثانية واحدة',
     m: 'دقيقة واحدة',
-    mm: 'دقائق %d',
+    mm: '%d دقائق',
     h: 'ساعة واحدة',
-    hh: 'ساعات %d',
+    hh: '%d ساعات',
     d: 'يوم واحد',
-    dd: 'أيام %d',
+    dd: '%d أيام',
     M: 'شهر واحد',
-    MM: 'شهرا %d',
+    MM: '%d أشهر',
     y: 'عام واحد',
-    yy: 'أعوام %d'
+    yy: '%d أعوام'
   },
   ordinal: n => n,
   formats: {
diff --git a/src/locale/cs.js b/src/locale/cs.js
--- a/src/locale/cs.js
+++ b/src/locale/cs.js
@@ -56,6 +56,7 @@ const locale = {
   months: 'leden_únor_březen_duben_květen_červen_červenec_srpen_září_říjen_listopad_prosinec'.split('_'),
   monthsShort: 'led_úno_bře_dub_kvě_čvn_čvc_srp_zář_říj_lis_pro'.split('_'),
   weekStart: 1,
+  yearStart: 4,
   ordinal: n => `${n}.`,
   formats: {
     LT: 'H:mm',
diff --git a/src/locale/sk.js b/src/locale/sk.js
--- a/src/locale/sk.js
+++ b/src/locale/sk.js
@@ -1,37 +1,87 @@
 // Slovak [sk]
 import dayjs from 'dayjs'
 
+function plural(n) {
+  return (n > 1) && (n < 5) && (~~(n / 10) !== 1) // eslint-disable-line
+}
+
+/* eslint-disable */
+function translate(number, withoutSuffix, key, isFuture) {
+  const result = `${number} `
+  switch (key) {
+    case 's': // a few seconds / in a few seconds / a few seconds ago
+      return (withoutSuffix || isFuture) ? 'pár sekúnd' : 'pár sekundami'
+    case 'm': // a minute / in a minute / a minute ago
+      return withoutSuffix ? 'minúta' : (isFuture ? 'minútu' : 'minútou')
+    case 'mm': // 9 minutes / in 9 minutes / 9 minutes ago
+      if (withoutSuffix || isFuture) {
+        return result + (plural(number) ? 'minúty' : 'minút')
+      }
+      return `${result}minútami`
+    case 'h': // an hour / in an hour / an hour ago
+      return withoutSuffix ? 'hodina' : (isFuture ? 'hodinu' : 'hodinou')
+    case 'hh': // 9 hours / in 9 hours / 9 hours ago
+      if (withoutSuffix || isFuture) {
+        return result + (plural(number) ? 'hodiny' : 'hodín')
+      }
+      return `${result}hodinami`
+    case 'd': // a day / in a day / a day ago
+      return (withoutSuffix || isFuture) ? 'deň' : 'dňom'
+    case 'dd': // 9 days / in 9 days / 9 days ago
+      if (withoutSuffix || isFuture) {
+        return result + (plural(number) ? 'dni' : 'dní')
+      }
+      return `${result}dňami`
+    case 'M': // a month / in a month / a month ago
+      return (withoutSuffix || isFuture) ? 'mesiac' : 'mesiacom'
+    case 'MM': // 9 months / in 9 months / 9 months ago
+      if (withoutSuffix || isFuture) {
+        return result + (plural(number) ? 'mesiace' : 'mesiacov')
+      }
+      return `${result}mesiacmi`
+    case 'y': // a year / in a year / a year ago
+      return (withoutSuffix || isFuture) ? 'rok' : 'rokom'
+    case 'yy': // 9 years / in 9 years / 9 years ago
+      if (withoutSuffix || isFuture) {
+        return result + (plural(number) ? 'roky' : 'rokov')
+      }
+      return `${result}rokmi`
+  }
+}
+/* eslint-enable */
 const locale = {
   name: 'sk',
-  weekdays: 'Nedeľa_Pondelok_Utorok_Streda_Štvrtok_Piatok_Sobota'.split('_'),
-  weekdaysShort: 'Ne_Po_Ut_St_Št_Pi_So'.split('_'),
+  weekdays: 'nedeľa_pondelok_utorok_streda_štvrtok_piatok_sobota'.split('_'),
+  weekdaysShort: 'ne_po_ut_st_št_pi_so'.split('_'),
   weekdaysMin: 'ne_po_ut_st_št_pi_so'.split('_'),
   months: 'január_február_marec_apríl_máj_jún_júl_august_september_október_november_december'.split('_'),
   monthsShort: 'jan_feb_mar_apr_máj_jún_júl_aug_sep_okt_nov_dec'.split('_'),
   weekStart: 1,
-  relativeTime: {
-    future: 'o %s',
-    past: 'pred %s',
-    s: 'niekoľko sekúnd',
-    m: 'minúta',
-    mm: '%d minút',
-    h: 'hodina',
-    hh: '%d hodín',
-    d: 'deň',
-    dd: '%d dní',
-    M: 'mesiac',
-    MM: '%d mesiacov',
-    y: 'rok',
-    yy: '%d rokov'
-  },
-  ordinal: n => `${n}º`,
+  yearStart: 4,
+  ordinal: n => `${n}.`,
   formats: {
     LT: 'H:mm',
     LTS: 'H:mm:ss',
     L: 'DD.MM.YYYY',
     LL: 'D. MMMM YYYY',
     LLL: 'D. MMMM YYYY H:mm',
-    LLLL: 'dddd D. MMMM YYYY H:mm'
+    LLLL: 'dddd D. MMMM YYYY H:mm',
+    l: 'D. M. YYYY'
+  },
+  relativeTime: {
+    future: 'za %s', // Should be `o %s` (change when moment/moment#5408 is fixed)
+    past: 'pred %s',
+    s: translate,
+    m: translate,
+    mm: translate,
+    h: translate,
+    hh: translate,
+    d: translate,
+    dd: translate,
+    M: translate,
+    MM: translate,
+    y: translate,
+    yy: translate
   }
 }
 
diff --git a/src/locale/th.js b/src/locale/th.js
--- a/src/locale/th.js
+++ b/src/locale/th.js
@@ -18,17 +18,17 @@ const locale = {
   },
   relativeTime: {
     future: 'อีก %s',
-    past: '%s ที่ผ่านมา',
-    s: 'ไม่กี่วิ',
-    m: 'นาที',
+    past: '%sที่แล้ว',
+    s: 'ไม่กี่วินาที',
+    m: '1 นาที',
     mm: '%d นาที',
-    h: 'ชั่วโมง',
+    h: '1 ชั่วโมง',
     hh: '%d ชั่วโมง',
-    d: 'วัน',
+    d: '1 วัน',
     dd: '%d วัน',
-    M: 'เดือน',
+    M: '1 เดือน',
     MM: '%d เดือน',
-    y: 'ปี',
+    y: '1 ปี',
     yy: '%d ปี'
   },
   ordinal: n => `${n}.`
diff --git a/src/locale/zh.js b/src/locale/zh.js
new file mode 100644
--- /dev/null
+++ b/src/locale/zh.js
@@ -0,0 +1,67 @@
+// Chinese [zh]
+import dayjs from 'dayjs'
+
+const locale = {
+  name: 'zh',
+  weekdays: '星期日_星期一_星期二_星期三_星期四_星期五_星期六'.split('_'),
+  weekdaysShort: '周日_周一_周二_周三_周四_周五_周六'.split('_'),
+  weekdaysMin: '日_一_二_三_四_五_六'.split('_'),
+  months: '一月_二月_三月_四月_五月_六月_七月_八月_九月_十月_十一月_十二月'.split('_'),
+  monthsShort: '1月_2月_3月_4月_5月_6月_7月_8月_9月_10月_11月_12月'.split('_'),
+  ordinal: (number, period) => {
+    switch (period) {
+      case 'W':
+        return `${number}周`
+      default:
+        return `${number}日`
+    }
+  },
+  weekStart: 1,
+  yearStart: 4,
+  formats: {
+    LT: 'HH:mm',
+    LTS: 'HH:mm:ss',
+    L: 'YYYY/MM/DD',
+    LL: 'YYYY年M月D日',
+    LLL: 'YYYY年M月D日Ah点mm分',
+    LLLL: 'YYYY年M月D日ddddAh点mm分',
+    l: 'YYYY/M/D',
+    ll: 'YYYY年M月D日',
+    lll: 'YYYY年M月D日 HH:mm',
+    llll: 'YYYY年M月D日dddd HH:mm'
+  },
+  relativeTime: {
+    future: '%s后',
+    past: '%s前',
+    s: '几秒',
+    m: '1 分钟',
+    mm: '%d 分钟',
+    h: '1 小时',
+    hh: '%d 小时',
+    d: '1 天',
+    dd: '%d 天',
+    M: '1 个月',
+    MM: '%d 个月',
+    y: '1 年',
+    yy: '%d 年'
+  },
+  meridiem: (hour, minute) => {
+    const hm = (hour * 100) + minute
+    if (hm < 600) {
+      return '凌晨'
+    } else if (hm < 900) {
+      return '早上'
+    } else if (hm < 1130) {
+      return '上午'
+    } else if (hm < 1230) {
+      return '中午'
+    } else if (hm < 1800) {
+      return '下午'
+    }
+    return '晚上'
+  }
+}
+
+dayjs.locale(locale, null, true)
+
+export default locale
diff --git a/types/plugin/isoWeek.d.ts b/types/plugin/isoWeek.d.ts
--- a/types/plugin/isoWeek.d.ts
+++ b/types/plugin/isoWeek.d.ts
@@ -1,4 +1,4 @@
-import { PluginFunc, QUnitType, ConfigType } from 'dayjs'
+import { PluginFunc, UnitType, ConfigType } from 'dayjs'
 
 declare const plugin: PluginFunc
 export = plugin

diff --git a/test/locale/cs.test.js b/test/locale/cs.test.js
--- a/test/locale/cs.test.js
+++ b/test/locale/cs.test.js
@@ -19,7 +19,7 @@ it('RelativeTime: Time from X', () => {
     [44.4, 'second'], // a few seconds
     [89.5, 'second'], // a minute
     [2, 'minute'], // 2 minutes
-    [43, 'minute'], // 44 minutes
+    [43, 'minute'], // 43 minutes
     [45, 'minute'], // an hour
     [3, 'hour'], // 3 hours
     [21, 'hour'], // 21 hours
diff --git a/test/locale/sk.test.js b/test/locale/sk.test.js
new file mode 100644
--- /dev/null
+++ b/test/locale/sk.test.js
@@ -0,0 +1,52 @@
+import moment from 'moment'
+import MockDate from 'mockdate'
+import dayjs from '../../src'
+import relativeTime from '../../src/plugin/relativeTime'
+import '../../src/locale/sk'
+
+dayjs.extend(relativeTime)
+
+beforeEach(() => {
+  MockDate.set(new Date())
+})
+
+afterEach(() => {
+  MockDate.reset()
+})
+
+it('RelativeTime: Time from X', () => {
+  const T = [
+    [44.4, 'second'], // a few seconds
+    [89.5, 'second'], // a minute
+    [2, 'minute'], // 2 minutes
+    [43, 'minute'], // 43 minutes
+    [45, 'minute'], // an hour
+    [3, 'hour'], // 3 hours
+    [21, 'hour'], // 21 hours
+    [1, 'day'], // a day
+    [3, 'day'], // 3 day
+    [25, 'day'], // 25 days
+    [1, 'month'], // a month
+    [2, 'month'], // 2 month
+    [10, 'month'], // 10 month
+    [1, 'year'], // a year
+    [2, 'year'], // 2 year
+    [5, 'year'], // 5 year
+    [18, 'month'] // 2 years
+  ]
+
+  T.forEach((t) => {
+    dayjs.locale('sk')
+    moment.locale('sk')
+    const dayjsDay = dayjs()
+    const momentDay = moment()
+    const dayjsCompare = dayjs().add(t[0], t[1])
+    const momentCompare = moment().add(t[0], t[1])
+    expect(dayjsDay.from(dayjsCompare))
+      .toBe(momentDay.from(momentCompare))
+    expect(dayjsDay.to(dayjsCompare))
+      .toBe(momentDay.to(momentCompare))
+    expect(dayjsDay.from(dayjsCompare, true))
+      .toBe(momentDay.from(momentCompare, true))
+  })
+})
diff --git a/test/locale/zh.test.js b/test/locale/zh.test.js
new file mode 100644
--- /dev/null
+++ b/test/locale/zh.test.js
@@ -0,0 +1,20 @@
+import dayjs from '../../src'
+import advancedFormat from '../../src/plugin/advancedFormat'
+import weekOfYear from '../../src/plugin/weekOfYear'
+import '../../src/locale/zh.js'
+import '../../src/locale/zh-cn.js'
+
+dayjs.extend(advancedFormat).extend(weekOfYear)
+
+const zh = dayjs().locale('zh')
+const zhCN = dayjs().locale('zh-cn')
+
+test('ordinal', () => {
+  expect(zh.format('wo')).toEqual(`${zh.format('w')}周`)
+})
+
+test('Meridiem', () => {
+  for (let i = 0; i <= 24; i += 1) {
+    expect(zh.add(i, 'hour').format('A')).toBe(zhCN.add(i, 'hour').format('A'))
+  }
+})

Invalid Thai translation on "fromNow" function when 1 day passed
**Describe the bug**
A clear and concise description of what the bug is.

Invalid result when i apply with one day passed

Current result is `วัน ที่ผ่านมา`

**Expected behavior**
A clear and concise description of what you expected to happen.

It should be `1 วัน ที่ผ่านมา`

**Information**
 - Day.js Version 1.8.21
 - OS: OSX
 - Browser Chrome  80.0.3987.122 
 - Time zone: GMT+07:00 (Indochina Time)


Thanks. 

Could you please send us a pull request to correct this in "Thai" (cause we don't know this language.)

This's easy, just to keep sync between 
https://github.com/iamkun/dayjs/blob/dev/src/locale/th.js#L19
and 
https://github.com/moment/moment/blob/develop/locale/th.js#L46
`relativeTime` section, and ignore the `ss` one.

Cheers.
test/timezone.test.js(1) test/timezone.test.js(2) test/timezone.test.js(3) test/timezone.test.js(4) test/locale/cs.test.js
test/locale/zh.test.js test/locale/sk.test.js