代维公司应具备所代维业务相关（）和（）。
参考答案：通信工程；维护经验
写出一个比﹣2大的负无理数：（ ）。
There ______ be a lot of manatees, but now they ______ endangered animals.[ ]
A. used to, become
B. would, become
C. used to, have become
D. would, have become
