从A、B、C、D四个选项中选出最佳选项填入空白处，并在答题卡上将该项涂黑
21．There was _______ time _______, if a lady got onto a crowded bus or train, a gentle man would immediately stand up and _______ her his seat.
A．a, when, offer B．/, when, give C．/, /, afford D．a, /, provide
22. Milk bottles need cleaning thoroughly before they are used again , they?
A．don’t B．mustn't C．meedn't D．aren't
23. Many scientists believe that global warming, if , will cause extreme climate changes this century .
A．not stopping B．no stop C．not stopped D．without stopping
24. Put yourself in situations where you will be forced to communicate in English, ____you will see more progress over time .
