The research lacks evidence, and therefore, its conclusions are doubtful.
| A．solid | B．fierce | C．severe | D．potential |
Was it ________ the conference of APEC that made Shanghai the focus of the world then?
| A．holding | B．to hold |
| C．held | D．having held |
Use your head. nothing taught by others can have the same effect on you as ________learned by yourself．
| A．those | B．what |
| C．that | D．the one |
________swallow（燕子）doesn’t make ________ summer.
| A．One; a | B．One ; ／ |
| C．A; the | D．A; ／ |
--Did Mary come to your birthday party?
--No. I __________ her, but she was away on business.
| A．would like to invite | B．would have liked to invite |
| C．must have invited | D．could invite |
All the preparations_________, we're ready to start.
| A．made | B．being made | C．having made | D．have been made |