（）验证了宇称不守恒定律。
A、泡利
B、杨振宁
C、李政道
D、吴健雄
参考答案：D
— My name is Nison. Shall I spell it for you?
— _____. [ ]
A. No problem
B. Nice to meet you
C. You are welcome
D. If you don't mind
乐乐买书用去8.55元，买钢笔用去3.2元，付给售货员15元，应找回多少元？
