去括号:(a+b)-2(a-b)=______.
根据去括号的方法:原式=a+b-2a+2b=-a+3b.
-Tina, you didn’t come to school yesterday. ______?
-I had a high fever.
A.How about you
B.What was the matter
C.Where did you go
D.What do you do
输卵管的上皮为(),由()和()组成。