若3xm+5y2与x3yn是同类项,则mn的值是( )
A.4
B.-4
C.64
D.-64
由同类项的定义,得
m+5=3n=2,
解得:m=-2,n=2,
则mn=4.
故选A.
The enlarged school campus is ______ the old one. [ ]
A. as three times big as
B. three times as big as
C. bigger three times than
D. as big as three times
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