I don’t become a serious climber until the fifth grade, ______ I went up to rescue a kite that was stuck in the branches of a tree.

A．when

B．where

C．which

D．why

汽车空调当制冷系统压力过高时，压力开关强行断开（）部件的工作。

A.冷凝器

B.蒸发器

C.压缩机电磁离合器

D.AC继电器