一列简谐横波沿x轴传播．t=0时刻的波形如图所示，质点A与质点B相

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问题选择题

一列简谐横波沿x轴传播．t=0时刻的波形如图所示，质点A与质点B相距1m，A点的振动速度沿y轴正方向；t=0.02s时，质点A第一次到达正向最大位移处．由此可知（　　）

A．此波的传播速度为12.5m/s

B．此波沿x轴正方向传播

C．从t=0时刻起，经过0.04s，质点A沿波的传播方向迁移了1m

D．在t=0.04s时，质点B处在平衡位置，速度沿y轴正方向

答案

答案：D

句型转换

同义句转换。

1. He didn't take part in the sports meeting because he was ill.

He didn't take part in the sports meeting ______ ______ his illness.

2. She said she was an artist, but actually she was a liar.

She said she was an artist, but ______ ______ ______, she was a liar.

3. He commanded that we (should) set out at once.

He commanded us ______ ______ ______ at once.

单项选择题

含大量油脂的中药，必须贮藏于

A．二冬
B．二术
C．二母
D．二活
E．二枫藤上述药物分别是指