The research is so designed that once _______ nothing can be done to change it.

A. visit B. paying a visit C. walk in D. walking in

A. Being founded B. It was founded C. Founded D. Founding

A. a policeman was asked to help B. the area was searching thoroughly

C. it was looked for everywhere D. she hurried to a policeman for help

A. the thief having caught B. catch the thief

C. the thief being caught D. the thief to be caught

A. it is necessary to have planted more trees B. many more trees need to plant

C. our city needs more trees D. we must plant more trees

A. to solving, making B. to solving, made C. to solve, making D. to solve, made

A. Having given B. To give C. Giving D. Given

A.You must know

B.In my opinion

C.As far as I know

D.You may be quite disappointed

A. carry out B. carrying out

C. carried out D. to carry out