采用粉煤灰硅酸盐水泥拌制的混凝土，其自然养护时间不得少于（）昼夜。
A.11
B.12
C.13
D.14
参考答案：D
As for the influence of Internet，nowhere（）the results more clearly than in the US.
A.we have seen
B.we had seen
C.seen we have
D.have we seen
“十一五”时期，东北地区人均G四年均增长( )。
A．16.8%
B．6.6%
C．8.8%
D．7.4%
