It has been widely accepted that only when the students take an active part in the class activities _______ the most effective.
| A．teaching will be | B．will teaching be |
| C．has teaching been | D．teaching has been |
The cost of renting a house in central Chengdu is higher than in any other area of the city.
| A．it | B．one | C．that | D．ones |
After completing and signing it, please return the form to us in the envelope .
| A．providing | B．provided |
| C．having provided | D．being provided |
Some insects the color of their surroundings to protect themselves.
| A．take in | B．take off |
| C．take on | D．take up |
The old couple often take a walk after supper in the park with their pet dog them.
| A．to follow | B．following |
| C．followed | D．follows |
—Do you have enough toall your daily expenses?
—Oh yes, enough and to spare.
| A．cover | B．spend | C．fill | D．offer |