____time,Chinese farmers have invented many farming techniques.
| A．Over | B．In | C．On | D．For |
As far as I know, he is seldom, _______ , late for school.
| A．if so | B．if never | C．if ever | D．if any |
．— My mum is a typist.
— I know this sort of work _______ skill and speed.
| A．asks for | B．looks for | C．calls for | D．pays for |
— You were out when I dropped in at your house.
— Oh, I _______ for a friend from England at the airport.
| A．was waiting | B．had waited | C．am waiting | D．have waited |
A new library is being built _______ there was a playground .
| A．that | B．in which | C．where | D．when |
．— Have you got your result of the final?
— Not yet．I was told that the papers _________-.
| A．were not grading | B．have already been graded |
| C．were still being graded | D．have not grading |