CAD表示（）。
A、计算机辅助设计
B、计算机辅助制造
C、计算机辅助教学
D、计算机辅助制图
参考答案：A
— You shouldn't have talked back to our teacher like that. It was awfully impolite.
— You are right. I _________ crazy at that moment. [ ]
A. could have been
B. can be
C. must have been
D. should have been
采取最大粒度小于150mm的入厂煤时，使用的尖铲尺寸长×宽（mm）约为（）。
A、250×300
B、450×300
C、300×250
D、450×375
