保持物质原来性质的粒子是[ ]
A．质子
B．电子
C．原子核
D．分子
答案：D
---Is your present pension sufficient to cover your cost of living?
---Enough and to spare. _________ [ ]
A. I can’t complain.
B. Serve me right!
C. I’ve had enough of it.
D. I can’t be too particular.
