It was not until 1911, _______ the first vitamin was identified, _______ people realized the importance of it．
A． when; which B． when; that
C． that; which D． that; that
We should think carefully about ______ Mr. Needham said at the meeting.
A. that B. what C. which D. /
Have you ever met with this case in your life you can't understand others even if they have said something several times？
A. where B. what C. that D. which
Only ____ as a translator _____ how important it is to understand foreign cultures.
A．when did I work; I realized
B．when I worked; I realized
C．when did I work; did I realize
D．when I worked; did I realize
Cao Cao’s tomb is reported ______ in China, which attracts nationwide attention.
A. being found B. to be found
C. having been found D. to have been found
With many forests being destroyed, huge quantities of good earth ______ each year.
A. is washing away B. is being washed away
C. are washing away D. are being washed away
