按照疾病自然史的三个阶段，三级预防是

A．病因预防
B．临床前期预防
C．临床期预防
D．疾病早期预防
E．症状明显期预防

Must I do the washing-up tonight?（）

A.No, you mustn‘t if you don‘t want.

B.Leave it if you‘re exhausted.

C.Washing-up is really exhausting.

D.Washing-up really takes up time.