New technology __________ to stop the students from cheating in the exam last year.
A．used B．is used C．was used
．--_________ will your parents come back to Shanghai?
--Maybe in a month.
| A．How far | B．How many | C．How soon | D．How often |
People _________ rivers for transportation since the beginning of history.
| A．used | B．have used | C．use | D．had used |
The new headmaster looks _________ to all the teachers and students of the school.
| A．friendly | B．seriously | C．probably | D．gently |
If the kids stay indoors all the time and get no exercise, they _________ weak.
| A．become | B．have become | C．will become | D．became |
At the meeting the boss was explaining his plan while his secretary_________ the notes.
| A．is taking | B．was taking | C．has taken | D．takes |