The scientists are studying the effects of human activities______the environment.
| A．in | B．at | C．on | D．with |
Someone is ringing the doorbell. Go and see ______ .
| A．who is he | B．who he is | C．who it is | D．who is it |
_________ I will visit Brazil during the 2016 Olympic Games.
| A．If I am possible | B．If it possible | C．If I possible | D．If possible |
___________, I have never seen anyone who’s as wise as John.
| A．As long as I have traveled | B．Now that I have traveled so much |
| C．.As I have traveled so much | D．Much as I have traveled |
You can make yourself _____ in English pretty well if you keep on speaking the language.
| A．understand | B．understanding | C．to understand | D．understood |
With dinner _____, the lady went on ____ some sewing.
| A．to prepare; to do | B．preparing; doing | C．prepared; to do | D．to be prepared; doing |