__________ by a greater demand of vegetables, farmers have built more green houses.
| A．Driven | B．Being driven |
| C．To drive | D．Having driven |
Water, _____ we cannot live, exists in the form of liquid, gas or solid.
| A．from which | B．on which | C．by which | D．without which |
His laziness ___________ his failing in the exam.
| A．result from | B．accounts for | C．because of | D．is on account of |
As we all know, smoking ___________ people’s health.
| A．is harmful to | B．do harm fo | C．does harmful to | D．harm |
_____ you have worked out the first problem, you may go on to work on the second.
| A．Even if | B．Unless | C．Now that | D．Though |
Most of the evidence was destroyed in the fire. _____, it would be almost impossible to prove Jim guilty.
| A．Anyhow | B．However | C．Besides | D．Thus |