问题
解答题
在平面上,七个边长均为1的等边三角形,分别用①至⑦表示(如图).从④⑤⑥⑦组成的图形中,取出一个三角形,使剩下的图形经过一次平移,与①②③组成的图形拼成一个正六边形.
(1)你取出的是哪个三角形?写出平移的方向和平移的距离.
(2)将取出的三角形任意放置在拼成的正六边形所在平面上,问:正六边形没有被三角形盖住时面积能否等于?请说明理由.

答案
解:(1)当取出的是⑦时,将剩下的图形向上平移1(如图1);
当取出的是⑤时,将⑥⑦向上平移2(如图2);
(2)能.理由如下:
每个小等边三角形的面积为,
五个小等边三角形的面积和为,
正六边形的面积为,
而<
<
,
所以正六边形没有被三角形盖住的面积能等于.

图1
图2
完形填空
完形填空。 | |||
Children like to copy what they hear. They copy their parents, their friends and even the TV. This teaches them how to 1 the language. Copying also does good to students of a second language. When you 2 foreigners speak English, repeat what they say as well as you can. Children don't practice grammar, but use the language to 3 that interest them. They don't 4 their vocabulary (词汇) or poor grammar. They find ways to express themselves, and they do it successfully. Students of English school also pay their attention to communication (交流). Look for 5 to talk with people in English. If you can't find a 6 to talk to, talk with other studens of English 7 . Start an English discussion group and talk about music, moves or anything that 8 you. Don't worry about 9 , what you want is to learn how to communicate easily and comfortably. Remember that you communicate successfully even with a small vocabulary. | |||
|