I like getting up very early in summer. The morning air is so good ______.
| A．to be breathed | B．to breathe |
| C．breathing | D．being breathed |
Lots of waste has been dumped into the river，which has led to________.
| A．lots of fish having been killed | B．kill lots of fish |
| C．lots of fish being killed | D．lots of fish to kill |
There was a________ look on his face when he met with the________ problem.
| A．confusing；confusing | B．confused；confused |
| C．confusing；confused | D．confused；confusing |
You’d better go there by train. The train ticket is________ the airplane ticket.
| A．as cheap three times as | B．as three times cheap as |
| C．three times cheaper than | D．cheaper three times than |
—Shall I give you a ride as you live so far away?
—Thank you，________.
| A．it couldn’t be better | B．of course you can |
| C．if you like | D．it’s up to you |
At times the balance in nature is____, resulting in a number of possibly unforeseen effects.
| A．confused | B．puzzled | C．disturbed | D．troubled |