22．After playing in the park for a few hours, the pupils gathered under trees _______shade and
________ down to eat their picnic lunch.
| A．provided; sit | B．provided; sat | C．providing; sitting | D．providing; sat |
—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 |
Only ________ according to the directions can the medicine be quite effective.
| A．taking | B．taken |
| C．being taken | D．having been taken |
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 |
—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 |
Every student in our class had an application form in his hand，but no one knew which office ________.
| A．to send it to | B．to send it |
| C．to be sent to | D．to have it sent |