第二节：课文背诵（20×0.5=10分）
Unit 3
By the way, did you know that this is because you become addicted in three different ways?
First, you can become (101)______ ______ ______ nicotine, which is one of the hundreds of chemicals in cigarettes. …… Secondly, you become addicted (102)______ ______. As you know, if you do the same thing over and over again, you begin to (103)______ ______ ________. Lastly, you can become mentally addicted.
Unit 4
However, the attitudes of scientists towards this rise are completely different. On the one hand, Dr Foster thinks that the trend which increases the temperature by 5 degrees would be (104) ______ ______. …….. (105)_____ _____ _____ _____, there are those, like George Hambley, who (106)_______ _______ _______ this view and believe that we should not worry. They predict that any warming will be mild with few bad (107)________ ________.
Unit 5
I have the greatest job in the world. I travel to unusual places and (108)________ ________ ________from all over the world. Sometimes ……, sometimes using (109)________ ________ and sometimes meeting local people and tourists, I am never bored.
Today, I am just as enthusiastic about my job as the day I first started. Having studied volcanoes now for many years, I am still amazed at their beauty as well as their (110)_______ _______ _______ great damage.
四个自由度。下平面限制了
三个自由度。因此，
两个自由度被重复限制，属过定位。除非齿轮的中心孔与端面的垂直度精度非常高，否则一般不允许使用。改进：将长心轴改为短销即可。