Few people paid full attention to their health conditions ________ they were seriously ill.
| A．when | B．if | C．until | D．after |
I’d like to ______ you _______ your success on the experiment.
| A．congratulations;on | B．congrgatulate;for |
| C．congratulations;for | D．congratulate; on |
It is generally believed that teaching is ______ it is a science.
| A．an art much as | B．much an art as | C．as an art much as | D．as much an art as |
He raised his voice to make himself _______ clearly by the audience.
| A．hearing | B．to hear | C．heard | D．hear |
There were too many people in the room and he could hardly find a chair ______.
| A．to sit | B．sit | C．to sit on | D．sitting |
Rather than ______ on a crowded bus, he always prefers ______ a bicycle.
| A．riding; to ride | B．riding; riding | C．ride; to ride | D．ride; riding |