证券投资基金与股票的区别表现在（）。

A.收益与风险不同

B.经济关系不同

C.投资工具性质不同

D.期限不同

E.投资者地位不同

—Do you know ______ last night?  

—Sorry , I don't know. But I  think he should go to bed early

because he will have an English exam this afternoon.  [ ]

A. when he goes to bed    

B. when he went to bed    

C. when did he go to bed    

D. when does he go to bed