The janitor（火炉工）, _______ in his regular work, _______ some steam immediately the pressure went up too high.
| A．absorbed; set off | B．absorbing; gave off |
| C．being absorbed; put off | D．absorbed; let off |
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______ his homework, he went on to preview the next lesson.
| A．Doing | B．To do | C．done | D．Having done |
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In 1989 an international law was passed to stop people _____ waste into the sea.
| A．to put | B．putting | C．not to put | D．not putting |
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—— John wants to see you today.
—— I would rather he ____ tomorrow instead of today.
| A．come | B．has come | C．should come | D．came |
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—— Don’t you have a watch?
—— But it has gone wrong. They say it’s not worth ______.
| A．being required | B．to be repaired | C．of repairing | D．repairing |
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This kind of work ______ great patience, so you should take your time.
| A．calls on | B．calls for | C．calls up | D．calls back |