_______ with his research work, the professor cared little about any other things.
| A．Occupying | B．Occupied |
| C．Having occupied | D．Being occupied himself |
It used to ______ that humans and animals were different and had little in common.
| A．believing | B．be believed | C．believe | D．believed |
The day breaks, _______ the birds are singing.
| A．for | B．because | C．since | D．As soon as |
________, I attended the meeting instead of him last week.
| A．He was ill | B．His being ill |
| C．He being ill | D．Him being ill |
When you read the book, you’d better make a mark ______ you have questions.
| A．at which | B．at where | C．the place where | D．where |
I didn’t see your sister at the cinema. If she ______, she would have met my brother.
| A．has come | B．did come | C．came | D．had come |