Arriving home，the boy told his parents about all the________which occurred in his dormitory.

A．occasions

B．incidents

C．matters

D．accidents

创伤愈合过程中2～3日后伤口收缩的主要原因是（）

A.纤维细胞的作用

B.水分的吸收

C.胶原纤维的作用

D.肌成纤维细胞的作用

E.胶原纤维玻璃样变