完形填空

    These days it is found that school students hardly have any sports. Is it because they have no 1 in sports? It may not be true. They often say they have 2 more important things to do.

    What are these important things? Exams! They have to 3themselves ready for all kinds of exams and tests in school. So many of them almost4bookworms(书呆子). In the past in the summer holidays, they could do5 they liked, but now they have to 6all their time preparing. So 7 have kept them away from going in for sports.

    Because of the pressure(压力) from 8 parents and teachers, they  9 to work harder and spend most of their time10 books. As for the students themselves, they don't want to11 the lessons because they want to further their studies. So it is necessary to give 12 of their spare time to their studies and 13 up their school sports.

    It's true a good education cannot go without physical training, the14 is true a quick mind hardly goes along with a 15body. Without a strong body, you can never do anything well, how can you make great success in life?

我很惊讶在这儿看见她。(be surprised to do sth.)

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如图所示，水平面（纸面）内间距为 $L$ 的平行金属导轨间接一电阻，质量为 $m$ 、长度为 $L$ 的金属杆置于导轨上。 $t=0$ 时，金属杆在水平向右、大小为 $F$ 的恒定拉力作用下由静止开始运动。 $t_0$ 时刻，金属杆进入磁感应强度大小为 $B$ 、方向垂直于纸面向里的匀强磁场区域，且在磁场中恰好能保持匀速运动。杆与导轨的电阻均忽略不计，两者始终保持垂直且接触良好，两者之间的动摩擦因数为 $\mu$ ，重力加速度大小为 $g$ 。求:

科学家仿照水母耳朵的结构和功能，设计了水母耳风暴预测仪。这种发明仪器的方法是（    ）

处理污水的絮凝剂聚合硫酸铁的化学式是Fe₂（OH）_n（SO₄）（3﹣ $\frac{n}{2}$ ）_m，下列有关该物质说法

不合理的是（   ）