You _______ to leave until you ________ your work.[ ]

I haven’t seen you for a long time. How’s it going — ____________.

In spring, we can often hear some birds_______ in our school.

依次填入下列横线处的词语，最恰当的一组是（ ）①为了搞清事故的原因，公安部门决定立案 。②上级多次派人来 这家工厂的财务工作，没有发现任何漏洞。③煤炭和石油都是现代工业所 的燃料和原料。

___ parents’ complaints, some cities havesignificantly cut school hours to give children more time for leisure and play