---He found a baby in his car when he came back from the supermarket. And         was crying for some milk.

--- When was        ?

---      was in 2000 when he was still in college.

A．it; that; This

B．he; this; It

C．she; it; This

D．it; that; It

在正常生产情况下，处于断开状态下的继电器接点称为常开接点，处于闭合状态下的接点称为常闭接点。