2．如图17所示，将质量M=1.20 kg的小沙箱，用轻质软绳（不可伸长）悬挂起来，开始处于静止状态，绳的长度l=0.80 m。用枪向沙箱发射质量m=0.05 kg的子弹，子弹以v₀=100 m/s 的速度向右水平击中小沙箱，并留在小砂箱中，小沙箱沿竖直面向上摆动。假设沙箱每次向左运动到最低点时就恰好有一颗同样速度的子弹射入沙箱，子弹射入沙箱的过程时间极短，可忽略不计，重力加速度g取10 m/s²，不计空气阻力。

   （1）求第一颗子弹射入沙箱的过程中子弹对砂箱的冲量大小；

   （2）求第一颗子弹射入沙箱并相对沙箱静止的瞬间，求砂箱对绳的拉力的大小；

   （3）求第一颗子弹射入沙箱后，砂箱摆动的最大高度；

   （4）要使沙箱摆动的最大角度小于60°，射入沙箱的子弹数目至少为多少

阅读下面短文，将标有A~F的段落或句子插入文章中题号为1~5的恰当位置，使全篇文章意义完整，结构连贯。注意：1)有一个选项是多余的；2)如选E请填涂AB；选F请填涂CD.

Freezing can keep food fresh and safe to eat. Freezing lowers the food temperature below zero degree Celsius. That is the point where water turns to ice.  1. , it is important to lower the temperature to between minus fifteen and minus twenty degrees Celsius as quickly as possible. The faster the freezing process is, the fresher the taste of the food.

Fruits and vegetables can be spread out inside the freezer. Once the food is frozen,   2. . Fruits are usually not cooked before they are frozen. This allows them to keep their fresh taste. The simplest way to prepare fruits is to cut them up and place them in a container inside the freeze before putting it in the container. This will keep it from sticking to the container. This is called the “dry pack” method.

 3. , The fruit is prepared along with some of its liquid or juice. You can ad some sugar to fruits that are naturally juicy. The sugar sweetens the fruit and brings out its natural juices.

 4. . Blanching means placing the vegetables in boiling water for a few minutes and then quickly placing them into very cold water. Blanching slows down the natural chemical aging process. All extra water should be removed before placing the vegetables into containers and freezing.   5. .

E. The second way is the “wet pack” method

F. Most foods can be stored frozen for up to one year

下面是一篇文章，请将标有A-F的段落插入文章中标号为1- 5的合适位置，使这篇文章意义完整，结构连贯；其中有一个段落是多余的。

A punctual （准时的）person is in the habit of doing a thing at the proper time and is never late in keeping an appointment.

      __1._____He is always in a hurry and in the end loses both time and his good name. A lost thing may be found again，but lost time can never be regained. Time is more valuable than material things.__ 2.______.The unpunctual man is for ever wasting and mismanaging his most valuable assets as well as the assets of others'. The unpunctual person is always complaining that he finds no time to answer letters or return calls or keep appointments promptly.____ 3.___. He knows that he can not get through his huge amount of work unless he faithfully attends to every piece of work when it has to be attended to .

Failure to be punctual in keeping one's appointments is a sign of disrespect towards others. If a person is invited to dinner and arrives later than the appointed time，he keeps all the other guests waiting for him. ___4._____.

Unpunctuality，moreover，is very harmful when it comes to doing one's duty，whether public or private. Imagine how it would be if those who are put in charge of important tasks failed to be at their proper place at the appointed time.__ 5.__

A. But the man who really has a great deal to do is very careful with his time and seldom complains because he lacks it.

B. The unpunctual man，on one hand，never does what he should do ahead of time.

C. In fact，time is life itself.

D. A man who is known to be habitually unpunctual is never trusted by his friends or

fellow men.

E. The unpunctual man，on one hand，never does what he has to do at the proper time.

F. All guests present ought to be respected by the host.

G. Usually this will be regarded as a great disrespect to the host and all other guests present.

（2009.湖北卷）:短文写作（共1题;满分25分，

假设你是华华，与英国网友汤姆约定用对方的母语通信，以提高各自的外语水平。最近你收到汤姆的电子邮件（附后），发现有一个成语使用不当。请根据下列要点，用英文回一封电子邮件。

要点:

1．不应使用 “无所不为”，应使用 “无所事事”;

2．说明这两个成语的用法;

3．给予鼓励。

注意:  1.词数为1叨左右;

2.参考释义:无所不为一do all kinds of bad things

无所事事一have nothing to do

3.除以上两个成语外，邮件中不得使用其它汉字或拼音;

4. 电子邮件的开头和结尾已为你写好（不计人你所写词数），但不得抄人答题卡。

附（汤姆的邮件）:

华华，你好!

近几天在忙什么事?有什么有意思的事吗?我们的学校放假了，所以这几天在家无所不为，饱食终日，只好上网发伊妹儿。没意思。我决定找份工作，做个自食其力的人。祝好!

汤姆

语法填空（共10小题；每小题1.5分，满分15分）

    阅读下面短文，按照句子结构的语法性和上下文连贯的要求，在空格处填入一个适当的词或使用括号中词语的正确形式填空，并将答案填写在答题卡标号为1~10的相应位置上。

         A farmer once organized a competition between his dog and his rabbit. He dug a hole in one of his biggest fields, and hid a carrot and a bone in it. He wanted to see ___1___ animal would find them first.

         The ___2__ (cheer) and optimistic rabbit threw himself into looking for the carrot, __3___ (dig) here and there, totally convinced that he would find it. But the dog, after sniffing around for a bit, ___4___ (lie) down and began to complain about how difficult it, was to find one bone in such a big field.

         The rabbit dug ___5__ hours, and with every new hole the dog complained even more about how difficult this was, even for the rabbit. ___6___ the rabbit thought that each hole dug was one hole less that needed digging. When there was no place in the whole field ___7__ (leave) to dig, the rabbit dug a tunnel right to __8___ the dog had been lying all the time. There he found the carrot and the bone.

                  This is how the dog lost the game. He had come to ___9__ right place at the very beginning but failed to find the bone ___10___ he only complained and didn't try at all.