若m、n满足 ︳m-2 ︳+ (n+3)2=0,则nm= .
9
∵m、n满足|m﹣2|+(n+3)2=0,∴m﹣2=0,m=2;n+3=0,n=﹣3;则nm=(﹣3)2=9.
I think that something has to be done to stop the air from being polluted, ______ ?
A.doesn't it
B.don’t I
C.don't they
D.haven't they
记忆过程包括()
A.识记、保持和遗忘
B.识记、再认和回忆
C.识记、保持和联想
D.识记、保持、再认或回忆