—Hi , Tom , why are you looking so tired ?
—I'm tried. Because I ______ the living room all day.
| A．painted | B．have been painting |
| C．have painted | D．had painted |
--Why didn’t you buy that hat at last?
-- ______ I liked the color of it, I did not like its shape.
| A．If | B．Because |
| C．While | D．Since |
Bob, along with several of his friends, ______to the art show, but sadly, they didn’t sell any of their paintings.
| A．has invited | B．had invited |
| C．was invited | D．were invited |
Crusoe’s dog became ill and died, ______made him very lonely.
| A．this | B．that | C．which | D．as |
It’s a fine day. Let’s go fishing, ________?
| A．won’t you | B．will you |
| C．don’t we | D．shall we |
No one knows what effects the GM material might have ________the food chain.
| A．on | B．for | C．to | D．with |