We are short of clean safe drinking water, which is found to be the ______ in many third world countries.
| A．example | B．event | C．case | D．object |
When I was a child, I __________ watch TV whenever I wanted to.
| A．should |
| B．could |
| C．must |
| D．need |
Since nobody gave him any help, he __________ have done the research on his own.
| A．can |
| B．must |
| C．would |
| D．need |
The children __________ lost in the woods; otherwise, they would have been at the lakeside camp as scheduled.
| A．must have got |
| B．must get |
| C．should have got |
| D．should get |
-Where did you get this book?
-I picked it up from a second-hand bookshop if you __________ know.
| A．must |
| B．will |
| C．can |
| D．shall |
Don't be angry with us. We __________ with you together, but we were busy with our final reports when you called in.
| A．would eat out |
| B．must have eaten out |
| C．should eat out |
| D．could have eaten out |