把一个长方形木框拉成一个平行四边形,它的周长[ ]
A.扩大
B.缩小
C.不变
答案:C
We must note that many people ____ the knowledge of first aid. [ ]
A. lack
B. lack of
C. lacking
D. are lacking
我国城市居住区绿化要求在()以上。
A、25%
B、30%
C、35%
D、40%