题干
—What time will Mr. Brown be back to China?
—Sorry. I don’t know______.
—Sorry. I don’t know______.
A：when did he go abroad
B：why he is going abroad
C：how soon will he be back
D：how long he will stay abroad
答案(点此获取答案解析）
D
="a," 
=b,则
等于( )
