①实验分组：

甲组：培养液+Y细胞+³H﹣TdR（³H标记的胸腺嘧啶脱氧核苷）+生理盐水

乙组：培养液+Y细胞³H﹣TdR+X（用生理盐水配制）

每组设置若干个重复样品．

②分别测定两组的CRD（细胞内的放射性强度），求每组的平均值．

③将各样品在适宜条件下培养合适时间后，测定CRD，求每组平均值并进行统计分析．

（要求与说明：答题时用X、CRD、³H﹣TDR表示相关名词：Y细胞是能增值的高等动物体细胞）请回答：

Dear Sandy,

    My family and I 1 in Nanjing, China. We are very happy. I am 2 student in No. 11 Middle School. Is our school 3? No, it isn't very big, but it's very beautiful. There 4 any swimming pools in it. But our school 5 two basketball courts. There is a garden and many tall trees in our school. There are about fifty 6 in our school. I am in Class 2, Grade 1. My classroom is 7 the second floor in 8 A. There are twenty girls and twenty-five boys in my class. Miss Fang is our Chinese teacher. 9 is a very good teacher. We all like her very much.

    May（愿） you be 10! Hope（希望） to see you soon（尽快）.

   Yours,

 Lily