①氨基酸      ②C，H，O，N等元素      ③氨基酸脱水缩合

④一条或几条多肽链连接在一起     ⑤多肽    ⑥蛋白质

一个数除以 $\frac{1}{5}$  ，这个数就扩大到原数的5倍．

“东方红，太阳升…他为人民谋幸福，他是人民的大救星．”这首歌里的“人民的大救星”是指在第一届中国人民政治协商会议上，被选举为中央人民政府主席的（　　）

      Liu Bing is Zhang Kun's friend,  and now he is in a high school in Ottawa.  This is a letter   1   Liu Bing to Zhang Kun. 
Dear Zhang Kun, 
       Thank you    2  your postcard.  I'm    3  to you in the reading-room.  Now I have many new friends here.  Henry is one of them.  He is my classmate.  He is 14   4  old.  His mother is a Canadian,  but his father is from Australia.  He often   5   me to go to his home for dinner   6  his parents. 
     His family like China very much.  At school,  we have many good teachers.  One of them is from the USA.  We   7   her Miss Green.  She teaches English.  Our French teacher is Mr.  Smith,  and he is from Paris.  He loves    8 very much,  and we all love him.  Our Chinese teacher is Mr.  Scott,  and he likes Chinese kung fu very much.  After school,  he often talks to me in Chinese.
   9 is your English now?  I want to know something    10  you very much, please write to me soon.
Yours,
Liu Bing