3/2×4/3×5/4×6/5×7/6×8/7×9/8的值是( )。
A．4
B．9/2
C．5
D．7/2
参考答案：B
If the prediction for the earthquake ________ more accurate, we would have been more prepared and many more lives would have been saved.
A．had been
B．was
C．has been
D．were
变速跑是队员在跑动中（）来完成攻守任务的一种方法。
A.突然改变方向；
B.利用速度的变换
C.突然制动速度
