下列说法正确的是(　　)

A．硅单质广泛用于光纤通讯

B．水晶项链是硅单质制品

C．利用盐酸刻蚀石英制作艺术品

D．硅酸钠可用于制备木材防火剂

In relation to the law of contract, distinguish between and explain the effect of:

(b) express and implied terms, paying particular regard to the circumstances under which terms may be implied in contracts. (7 marks)