题干
—Talking loudly in a library is impolite.
—In fact, we should also take care not to cough or sneeze loudly in public.
—In fact, we should also take care not to cough or sneeze loudly in public.
A：look after
B：be careful
C：take care of
D：look up
答案(点此获取答案解析）
B
（
为虚数单位）的虚部是（ ）
