29. The new law has come into _____; surely it will have _____on industry of the country.

A. affect; an effect　　 B. effect; affect　

　C. effect; an effect　　 D. an effect; an effect

28.The child should be punished. You should’t let him _______ telling lies.

　 A. keep away from　 B. keep away with　

　 C. get away from　 D. get away with

27.She did not take the advice that she ___ at rush hour, so she got lost.

A. not travel　　 B. did not go　 C. should travel　 D. goes shopping

26. He picked up an envelope ____50 dollars in it.

A. containing　　　 B. contained　

C. which contains　 D. which was contained

25. Jasper is a great painter. He is _____ Picasso.

A. as a great as　　　　　 B. as great painter as　

C. as great a painter as　 D. so great a painter as

24.I’d like to do something for you_______ everything you have done for me.

　 A. in exchange　 B. in turn　 C. in return for　 D. in terms of

23.It was very _______ of you to let us know you were going to be late for the party.

　 A. particular　 B. merciful　 C. considerate　 D. considerable

22.According to the school rules, no student_______ go out of the school after eleven o’clock at night without the teacher’s permission.

　 A. will　　 B.shall　　 C. must　 D. may

第一节：单项填空(共15小题，每小题1分，满分15分)

从A、B、C、D四个选项中，选出可以填入空白处的最佳选项。

21.It is _______ great shock for all of us to hear _______ news that three university students lost their lives because of saving others.

　 A. the;a　 B. /;a　 C. /;/　 D.a;the

17．(12分)自由电子激光器是利用高速电子束射入方向交替变化的磁场，使电子在磁场中摆动着前进，进而产生激光的一种装置.在磁场中建立与磁场方向垂直的平面坐标系xoy，如图甲所示.方向交替变化的磁场随x坐标变化的图线如图乙所示，每个磁场区域的宽度，磁场的磁感应强度大小T，规定磁场方向垂直纸面向外为正方向.现将初速度为零的电子经电压V的电场加速后，从坐标原点沿x轴正方向射入磁场.电子电荷量C，电子质量m取kg，不计电子的重力，不考虑电子因高速运动而产生的影响.

　　(1)电子从坐标原点进入磁场时的速度大小为多少?

　　(2)请在图甲中画出x=0至x=4L区域内电子在磁场中运动的轨迹，计算电子通过图中各磁场区域边界时位置的纵坐标并在图中标出；

　　(3)从x=0至x=NL(N为整数)区域内电子运动的平均速度多大