28. —Did you hear Tom was criticized for his spelling mistakes in his English composition?
—Yes, but a more careful person ________ so many mistakes.
| A．wouldn’t make | B．needn’t have made |
| C．shouldn’t make | D．wouldn’t have made |
Scientists say it may be five or six years ____ it is possible to test this medicine on human patients.
| A．since | B．after | C．before | D．when |
Every minute must be made full use of ____ our lessons, for the final examination is coming.
| A．going over | B．to go over | C．go over | D．to going over |
The foreigner does speak Chinese well, but of course not _____ we Chinese.
| A．as fluent as | B．more fluent than | C．so fluently as | D．much fluently than |
The reason _____ he refused to attend the meeting was that they didn’t give him an invitation earlier.
| A．how | B．which | C．why | D．because |
—Thank you for joining in our conversation tonight.
—_____.
| A．It’s my duty | B．It’s all right | C．It’s my pleasure | D．With pleasure |