If _______ in class, you will have to cl
题型：选择题
问题：
If _______ in class, you will have to clean the classroom for a week as a punishment. [ ]
A. caught sleeping
B. caught to sleep
C. catching sleeping
D. to catch to sleep
题型：选择题
If _______ in class, you will have to clean the classroom for a week as a punishment. [ ]
A. caught sleeping
B. caught to sleep
C. catching sleeping
D. to catch to sleep
是不稳定的，能自发的发生衰变。
衰变反应方程：
____________。
衰变为
，经过____________次α衰变，____________次β衰变。