Chemical processes _______in the treatment of materials for clothes _______the environment badly in some countries nowadays．
| A．involve；damaging | B．involved；damaged |
| C．involving；damage | D．involved；damage |
—Would you like some more chicken?
—No，thanks. I am ________a diet and I’m trying to ________weight.
| A．on；lose | B．on；put on |
| C．in；have | D．in；lose |
He sat at the desk, __________ a novel.
| A．read | B．to read | C．reading | D．Reads |
Great changes _______ in China in the past 20 years.
| A．took place | B．have taken place |
| C．were taken place | D．have been taken place |
The world today _____ different without the amazing discoveries produced by great scientists.
| A．were | B．had been | C．would be | D．would have been |
I was surprised to find the snack shops around the school empty; the students everything!
| A．had been buying | B．had bought |
| C．have bought | D．have been buying |