—Hi，Mary.Would you like to go to the concert this evening?
—Sorry，Tom.________ tomorrow's lessons，I have no time to go out with you.
A．Not preparing B．Not having prepared
C．Not to prepare D．Being not prepared
The man we followed suddenly stopped and looked as if ________ whether he was going in the right direction.
A．seeing B．having seen
C．to see D．to have seen
Only ________ according to the directions can the medicine be quite effective.
A．taking B．taken
C．being taken D．having been taken
—We didn't find the Blacks ________ the lecture.
—No one had told him about ________ a lecture the following day.
A．to attend；there to be B．attending；there being
C．attended；there be D．attend；there was
A few days after the interview，I recevied a letter ________ me admission to the university.
A．offering B．offered
C．having offered D．to be offered
—Why do you look sad?
—There are so many problems ________.
A．remaining to settle B．remained settling
C．remaining to be settled D．remained to be settled
