______ no doubt that 100 years ago animal testing was cruel but today animals in experiments are very well taken care of.
| A．It is | B．There is | C．This is | D．That is |
—I wonder if you could go with me to the supermarket.
—Sorry. I _______ my experiment report all the morning and haven’t finished yet.
| A．write | B．was writing |
| C．have written | D．have been writing |
_______ a small number of Australians are bitten by spiders each year, most recover without any medical treatment.
| A．While | B．Unless | C．When | D．Because |
This morning I saw an old friend of mine in the street by ______.
| A．event | B．accident | C．affair | D．matter |
Everyone should _______________ the environment.
| A．make a contribution to protect | B．make contribution to protecting |
| C．contribute in protecting | D．make contributions to protecting |
—Listen, Lily is playing the piano!
—Wow, how sweet the music ______!
| A．is heard | B．hears | C．is sounding | D．sounds |