用0.2％NaF溶液含漱防龋，频率应为（） A.每天一次 B.隔天一次

搜题请搜索小程序“爱下问搜题”

问题单项选择题

用0.2％NaF溶液含漱防龋，频率应为（）

A.每天一次

B.隔天一次

C.每隔三天一次

D.每周一次

E.每月一次

答案

参考答案：D

选择题

—Yang Liwei has won great honour for our country.

—Who is Yang Liwei?

—What a question! It is surprising that ________ the first spaceman in China.

A．you didn’t know our national hero

B．to you not to know him

C．you should know nothing about

D．you knew nothing about him

问答题简答题

简述闪烁探测器。