源项控制法就是想方设法（）工作现场辐射源的辐射强度。
A.增加
B.无视
C.维持
D.降低
参考答案：D
- Where have you been all day?
- We _________ some beautiful children and we couldn’t get away
from them until it was dark．
A．meet
B．have been met
C．met
D．have been meeting
出生率习惯上用（）。
A.百分率
B.千分率
C.万分率
D.十万分率
E.无所谓
