Joan didn’t say anything at first and then ________ crying.
A burst out B burst into C burst on D burst upon
While watching television, _______________________.
| A．the doorbell rang | B．we heard the doorbell ring |
| C．there was someone knocking at the door | D．we heard the doorbell rung |
_______ by greater demand of vegetables, farmers have built more green houses.
| A．Driven | B．Being driven | C．To drive | D．Having driven |
________ they become dirty, the lakes are not able to clean themselves
| A．Once | B．Since | C．As | D．Because |
I think he is ________ to win, but I’m not sure.
| A．possible | B．likely | C．probably | D．certain |
The weather turned out to be fine yesterday, I _____ the trouble to carry my umbrella with me.
| A．should have taken | B．could have taken |
| C．needn’t have taken | D．mustn’t have taken |