______ 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 |
. ---What has Tom been doing recently?
---I don’t know, ___________care.
| A．nor do I | B．nor I do | C．neither am I | D．neither I am |
I’ve worked with children before so I know what___________in my new job.
| A．expected | B．to expect | C．to be expecting | D．expects |
He studied hard at school when he was young, ___________leads to his success in his later life.
| A．what | B．which | C．that | D．so that |
Mr. Smith is one of the foreign experts who ___________in China.
| A．works | B．is working | C．are working | D．has been working |
They are letting us use their computers, and ___________we are giving them the results of our research.
| A．in turn | B．in theory | C．in return | D．in general |