My father retired in 2008, _____ he has been devoting his time to gardening.
| A．at which | B．since when |
| C．when | D．after that |
--- I wonder if I could use your telephone?
--- _________.
| A．I wonder how | B．I don’t wonder |
| C．Sorry, it’s out of order | D．No wonder, here it i s. |
The watch ______ unnoticed for several days before I found it.
| A．had laid | B．had lain | C．had been laying | D．had been laid |
—What do you think of his opinion?
—None has given me ___________ piece of advice.
| A．a better | B．a best | C．the best | D．the better |
It has been proved _______ eating vegetables in childhood helps to protect you against serious illnesses in later life.
| A．if | B．that | C．what | D．when |
It is reported that the United States uses ____ energy as the whole of Europe.
| A．as twice | B．twice much | C．twice much as | D．twice as much |