Tom with his friends ______ volleyball since three o’clock.
| A．has been playing | B．is playing | C．have been playing | D．have played |
The glass of water is too hot. I prefer some cold __________ water.
| A．boiled | B．boiling |
| C．to boil | D．having boiled |
Scientists have reached the disturbing conclusion __________ the amount of the solar energy reaching the Earth's surface has been gradually falling.
| A．that | B．why |
| C．whether | D．what |
Such a grammar mistake is __________ among the beginners of English study.
| A．normal | B．common |
| C．general | D．ordinary |
A person's __________ body temperature is about 37℃.
| A．ordinary | B．normal |
| C．common | D．usual |
The program, __________ at improving the students' ability of listening and speaking, will surely be a success.
| A．to aim | B．aimed |
| C．to aiming | D．having aimed |