昆虫的一个世代是昆虫的（）周期。
A、1个生命
B、1年生活
C、1个活动
D、都不是
参考答案：A
The boss looked very worried and demanded that the work________before we went home.
A．wound be finished
B．was finished
C．must be finished
D．be finished
阀门井的净高为多少？
