题干
You just catch a cold. There is nothing to ___________.
A：worry about
B：worry
C：be worrying
D：be worry
答案(点此获取答案解析）
A
You just catch a cold. There is nothing to ___________.
A：worry about
B：worry
C：be worrying
D：be worry
的导函数为
，则
（
为虚数单位） （ ）