While building a tunnel through the mountain, ________ .
| A．an underground lake was discovered |
| B．there was an underground lake discovered |
| C．a lake was discovered underground |
| D．the workers discovered an underground lake |
Listen to the two girls by the window. What language_________.
| A．did they speak | B．were they speaking |
| C．are they speaking | D．have they been speaking |
My brother is an actor. He _____in several films so far.
| A．appears | B．appeared | C．has appeared | D．is appearing |
Years ago we didn’t know this, but recent science ______that people who don’t sleep well soon get ill.
| A．showed | B．has shown | C．will show | D．is showing |
Father ____ for London on business upon my arrival, so I didn’t see him.
| A．has left | B．left | C．was leaving | D．had left |
They ______on the program for almost one week before I joined them, and now we _____on it as no good results have come out so far.
| A．had been working; are still working | B．had worked; were still working |
| C．have been working; have worked | D．have worked; are still working |