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问题 选择题

30. Even if you are an experienced teacher, you sometimes ____ make some mistakes.

A．can

B．must

C．should

D．Will

答案

答案：A

选择题
函数y=（2x-2）2+（2-x+2）2，通过换元t=ϕ（x），变成二次函数y=t2-4t+m（m为常数），则ϕ（x）=（　　）
A．2x+2-x B．2x-2-x C．2x-21-x D．2x+21-x
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选择题

________ I heard the song by Taylor Swift, I was kept in its power.

A．First time

B．For the first time

C．The first time

D．At the first time
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