Loulan is believed __________ over by sandstorms gradually from AD200 to AD400.
A．to cover B．to be covered
C．to have covered D．to have been covered
They were having an argument about __________ turn it was to do the cooking.
A．which B．what C．whose D．who
His son has __________ the running of his company, including six London theatres.
A．taken up B．taken off C．taken on D．taken over
The new road is __________ of the old one.
A．more than three times the length
B．three times more than the length
C．more than the length
D．more three times than the length
The possibility __________ pleasant smells might reduce pain has recently been suggested by new research.
A．where B．what C．which D．that
Thanks to _____ help from his teachers and classmates, he has made _______ rapid progress in his studies.
A．不填；a B．the; 不填 C．the; a D．a; the
