This problem may _______ more serious ones if left unsolved.
| A．come across | B．refer to | C．carry on | D．lead to |
We had to stay at home ________ a heavy rain.
| A．for | B．since | C．because | D．because of |
You’d better have your bike ________, or it’ll get you into trouble.
| A．repair | B．to repair | C．repairing | D．repaired |
--- Do you know our city at all?
--- No, this is the first time I ________ here.
| A．was | B．came | C．have come | D．had come |
He told us ________ again.
| A．to never do that | B．never to do that |
| C．never do that | D．never did that |
---When will the plane leave?
---It ________ very soon.
| A．leaves | B．is leaving | C．has left | D．had left |