The diversity of the original American Indian settlers was not quite as great as _________of the 18th, 19th.
| A．those | B．one | C．that | D．it |
We won't know whether it will be successful. We won't know whether there will be good _____.
| A．ends | B．results | C．effects | D．causes |
The government placed _____ on the numbers of foreign cars that could be imported.
| A．limitations | B．restraint |
| C．requirements | D．restrictions |
. He ate what he could, and gave the _____ of the food to the birds.
| A．remain | B．uneaten | C．rest | D．part |
Experts say walking is one of the best ways for a person to _____ healthy.
| A．preserve | B．stay | C．maintain | D．reserve |
. Jack almost fell off the cliff, but managed to _____ until help came.
| A．keep on | B．catch on | C．count on | D．hang on |