The only system I know ____ will help you remember what you have heard at a lecture is the system of keeping notes.
| A．what | B．that | C．where | D．one |
As your instructor(教师) advised, you ought to spend your time on something ____ researching into.
| A．precious | B．worth | C．worthy | D．valuable |
_____ the fact that his initial(开始的)experiments had failed, Pro. White persisted (坚持) in his research.
| A．Because of | B．As to | C．In spite of | D．In views of |
—Do you have enough to ________ the cost of your board at school?
—Oh yes, enough and to spare.
| A．cover | B．spend | C．fill | D．spare |
When I talked with my grandma on the phone, she sounded weak, but by the time we ___ up, her voice had been full of life.
| A．were hanging | B．had hung | C．hung | D．would hang |
Gun control is a subjectAmericans have argued for a long time .
| A．of which | B．with which | C．about which | D．into which |