（）的作用是：电梯轿厢超越上下端站平层位置，开关则动作，使电梯停止向危险方向运行，向安全方向运行不受影响。

A、端站强迫减速开关

B、端站限位开关

C、端站极限开关

D、缓冲器开关

用方框内所给词的适当形式完成下列对话，其中有两个单词为多余选项。

A：Lucy !. Where ____1___you?

B：I'm Here，in my bedroom.

A：What are you doing?

B：Oh，I'm___2__my room. It's dirty.

A；Where's your sister?

B：She's on the ___3____.

A：What is she doing there?

B：She's ____4___a kite with her classmate, Chen Jie.

A：Come here,dear. I need you help.

B：OK. I'm___5____.