20．Tell John not to leave the house unless he_____________that the lights .
| A．will make sure，turn off | B．makes sure，are turned off |
| C．will make sure，will turn off | D．makes sure，will be turned off |
________evidence that language acquiring ability must be stimulated.
| A．If being | B．It is | C．There is | D．There being |
The professor could hardly find sufficient grounds _____his arguments in favor of the new
theory.
| A．to be based on | B．to base on |
| C．which to base on | D．on which to base |
My train arrive in New York at eight o'clock tonight. The plane I would like to take from
there ______by then.
| A．would leave | B．will have left | C．has left | D．had left |
Many workers were organized to clear away remained of the World Trade Center.
| A．those | B．that | C．what | D．where |
The organization broke no rules, but ______had it acted responsibly.
| A．neither | B．so | C．either | D．both |