题目

在干冰晶体中每个CO2分子周围紧邻的 CO2分子有___________个,在晶体中截取一个最小的正方形；使正方形的四个顶点部落到CO2分子的中心，则在这个正方形的平面上有___________个C02分子。 答案：12个    4个完型填空。（每小题0.5，计5分）Perhaps you ride a bicycle to school. Riding a bicycle can be great fun. Do you know how to ride a bicycle    41  ?Careful boys and girls learn to ride their bicycle well    42   they go out on the road. How can you tell    43   you are a good rider or not?If you can ride a bicycle in a straight line, you can ride well. If you can’t, you should practice riding    44   a safe place. To be safe on a bicycle, you    45   to use both hands and both feet.    46   your feet on the pedals (脚踏) and your hands on the handle bars (把手) at all times.Do you have a basket on your bicycle? If so, put your books and other things in the    47 . You know that your bicycle is built for one person. It is not safe to carry anyone   48   you.   49 is this so? Keep   50 safe by safety rules when you ride on a bicycle. 【小题1】 A. safe  B. safelyC. save【小题2】 A. beforeB. after   C. until【小题3】 A. thatB. howC. whether【小题4】 A. inB. atC. to【小题5】 A. mustB. needC. may【小题6】 A. KeepB. MakeC. Let 【小题7】 A. boxB. bagC. basket【小题8】 A. toB. forC. with 【小题9】 A.WhyB. WhatC. How【小题10】 A. yours B. youC. yourself