A:150°
B:120°
C:60°
D:30°
—Your T-shirt is nice. It must be expensive.
—Not at all. I only spend $10 it.
—Excuse me. Where is the entrance ________ the meeting room?
—It is just on the left of the lobby.
先化简,再求值:﹣a2b+(3ab2﹣a2b)﹣2(2ab2﹣a2b),其中 a=﹣1,b=﹣2.