担任委派会计岗位的人员年龄不得超过()周岁。
A、40
B、42
C、45
D、50
参考答案:C
设D是矩形区域:0≤x≤π/4,-1≤y≤1,则xcos2xydxdy等于:()
A.0
B.-1/2
C.1/2
D.1/4
选择填空。
You must study English well ______ it is very useful. [ ]
A.but
B.because
C.so