______ it have been the failure to pick up directions from the ground control that caused the air crash?
| A．Must | B．Could | C．Would | D．Should |
Given that real estate regulation has failed more than once in the past, there are many who____ that house prices will start rising again.
| A．inspect | B．suspect |
| C．blame | D．suggest |
The traveling plan, _____ most of people objected, was in no way practicable.
| A．which | B．to which |
| C．with which | D．just as |
It’s very wise of you to____ well-trained workers ____ untrained ones in the assembly line.
| A．substitute; for | B．substitute; with |
| C．replace; by | D．replace; with |
----Jane, you’ve made such great efforts that you are____ to pass the exam.
----It is very kind of you to say so, Mr. Smith.
| A．easy | B．bound |
| C．possible | D．unlikely |
---Why didn’t you come to Mike’s birthday party yesterday?
-----Well, I _______, but I had something important to do at the moment.
| A．should | B．must |
| C．should have | D．must have |