A:k1=k2
B:k1>k2
C:k1<k2
D:无法比较
在初中即将毕业之际, 请你以张明的名义给英国笔友Brian写一封感谢信, 要点提示如下:
three years ago
a new comer, have no friends and feel lonely…..
During three years
Brain have written many letters to help you in different ways:
Encourage you to make more friends.
Tell you the ways how to learn English well
…….
You have changed a lot, for example, ……..
invite him to come to Hangzhou to pay a visit…….
要求:
①词数:80--100个
②信的开头和结尾已给出, 不计入总词数
③要点齐全, 行文连贯, 可适当发挥
Dear Brian,
How time flies! We have been friends for three years. I'm writing to thank you for your help!
Three years ago, ……
Hope to see you soon!
Yours,
Zhang Ming
某校要从高一、高二、高三共2010名学生中选取50名组成2010年上海世博会的志愿团,若采用下面的方法选取;先用简单随机抽样的方法从2010人中剔除10人,剩下的2000人再按分层抽样的方法进行,则每人入选的概率 ( )