呼吸过缓是指呼吸频率小于10次/分。()
参考答案：对
People have lots of problems living in the central Australian desert, ____ the lack of water is the most serious one.
A．of which
B．which
C．for which
D．where
点火系次级电压随转速升高而（）的现象，是发电机高速时容易断火原因。
A．升高；
B．降低；
C．不变；
D．失效
