238. --- Ought he to get down to his work at once?
--- Yes, he _____.
ought B. ought to C. must D. should to
34．By no means _____ of our students to drop out of school．
| A．will we allow | B．we will allow |
| C．we allow | D．must we allow |
33．— Can I help you?
— Do you have any of Michael Jackson's CDs ? I would like to buy _____．
| A．it | B．one | C．that | D．Those |
32．Tens of thousands of trees _____ in the area in the past few years．
| A．have been planted | B．were planted | C．have planted | D．had planted |
31．— I'm wondering why the visitors chose to stay with the host family．
— _____real local life．
| A．Experiencing | B．Experience | C．To experience | D．Having experienced |
30．How long do you think it will be _____ we can find a new water source?
| A．after | B．before | C．when | D．Since |