（2014届陕西省西工大附中高三第七次适应性训练 ）
Sheldon could have defeated Howard in the match, but he _______ too careless at the last minute.
| A．is | B．was | C．has been | D．had been |
It was nine years ago, ________ I went to the UK for the first time, ________ I began to learn English.
| A．that; where | B．when; that |
| C．that; when | D．when; which |
That old man ________to be more than a hundred years old, but he looked much younger than most of the ninety-year-olds.
| A．expressed | B．explained |
| C．stated | D．claimed |
Something must be done to stop cutting down trees. ________ all the trees are cut down, the valuable soil will be washed away by the heavy rain.
| A．Whether | B．Unless |
| C．Once | D．Until |
Mr. Black, as far as I know, is said _______ a book on the history of the Ming Dynasty, which turns out to be a bestseller.
| A．to write | B．to have written |
| C．to be writing | D．having written |
The contributions of some companies have ________ much improvement in the teaching and learning environment in this university.
| A．carried out | B．changed from |
| C．resulted in | D．succeeded in |