Everyone will go through life's stages of ups and downs, ________ self­respect plays a key role in the maturity(成熟) of a person.

A．when

B．which

C．as

D．that

热固性胶粘剂有环氧树脂、（）、不饱和聚酯和聚酰胺几种。

A.成膜树脂

B.饱和聚酯树脂

C.硅酸盐

D.聚丙烯酸酯