In the past, ice used to ______ used to ______ the air in a room.
| A．be ;cooling | B．be; cool | C．being; cool | D．being; cooling |
33. –There were already five people in the car but they managed to take me as well.
--It _____ a comfortable journey.
| A．can’t be | B．shouldn’t be | C．mustn’t have been | D．couldn’t have been |
32. –Why, I couldn’t get you on the phone this morning.
--We _____ tennis in the yard when you called.
| A．must be playing | B．could be playing |
| C．must have played | D．must have been playing |
31. Tom as well as his classmates _____ Japanese in Japan.
| A．are studying | B．have studied | C．studies | D．Study |
30. Let Harris play with your toys as well, Clare. You must learn to _____.
| A．support | B．care | C．share | D．Spare |
29. New ways _____ to prevent the river _____.
| A．have found out, from polluting |
| B．have found, from being polluted |
| C．have been found out, from being polluted |
| D．have been found, from being polluted |