Whenever he was asked why he was late fo

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问题选择题

Whenever he was asked why he was late for class, he would answer carelessly, always _____ the same thing. [ ]

A. saying

B. said

C. to say

D. having said

答案

答案：A

单项选择题

对原发性肝癌早期诊断最有价值的是（）。

A．甲胎蛋白测定

B．癌胚抗原测定

C．B超检查

D．CT检查

E．腹部平片

单项选择题

-平面简谐波沿z轴正向传播，已知x=-5m处质点的振动方程为y=Acosπt，波速为u=6m/s，则波动方程为( )。

A．y=Acosπ[t-(x-5)/6]
B．y=Acosπ[t-(x+5)/6]
C．y=Acosπ[t+(x+5)16]
D．y=Acosπ[t+(x-5)/6]