—__________do you go to see your uncle?
—Three times a month.
| A．How long | B．How many | C．How often | D．How old |
His speech was so _________ that it makes me feel _________.
| A．bored; asleep | B．boring; asleep |
| C．boring; sleepy | D．bored; sleeping |
—You can hardly imagine the pleasure of chatting with friends on Wechat (微信).
—Really? But it ______ cause you much trouble if someone get your personal information.
| A．may | B．must | C．need | D．should |
_________, when Marx was already ________, he began to learn Russian.
| A．In 1870s; in his fifties | B．In 1870s; in fifties |
| C．In the 1870s; in his fifties | D．In the1870s; in fifties |
He made a serious mistake, but he took action to change that _________ it got worse.
| A．until | B．when | C．because | D．before |
We should try our best to make ______ world that is safer, cleaner and healthier than ____ one we are living in now.
| A．the; / | B．a; / | C．the; the | D．a ;the |