1. INTRODUCTION  
2. THE SAMPLE  
3.2. JCMT SCUBA-2 Observations  
3.3. 45m Observations  
3.4. Infrared Data  
4. RESULTS  
4.1. Identification of Binary/Multiple Systems  
4.2. Properties of the Natal Dense Cores  
4.3. $N_{2}H^{+}$ Maps of Protostellar Cores  
4.4. Separation of Protostars in Binary/Multiple Systems  
5. DISCUSSION  
5.1. Origin of the Multiplicity of Protostars in Dense Cores  
5.3. Different Evolutionary Stages of Protostars in Binary/Multiple Systems  
6. SUMMARY