原式可化为:
(43)2n=(43)3-n,
于是2n=3-n,
解得n=1,
故选B.
— _____ do you usually come to school?
—By bike.
A. How B. What C. Where
下列与解决我国水资源空间分布不均有关的工程是
A.西气东输
B.南水北调
C.西电东送
D.海水淡化