—I heard Mary and Peter fell in love with each other.

—They'd better not, because it's bad for their study ___________. [ ]

A. in and out

B. near or far

C. more or less

D. up and down

医院感染散发病例应在多长时间内上报

A．4小时
B．6小时
C．12小时
D．24小时
E．48小时