CDU的全称是Combing&（） Unit。

（）terrible weather we’ve been having these days！

填空题（）terrible weather we’ve been having these days！

It was about 600 years ago （） the first clockwith a fac...

填空题It was about 600 years ago （） the first clockwith a face and an hour hand was made.

恢复和并发控制的基本单位是（）。

填空题恢复和并发控制的基本单位是（）。