— Robert is indeed a wise man.
— Oh, yes. How often I have regretted __________ his advice!
| A．to take | B．taking |
| C．not to take | D．not taking |
____ all behavior is learned behavior is a basic assumption of social scientists.
| A．Nearly | B．That nearly | C．It is nearly | D．When nearly |
By the middle of the 21st century , the vast majority of the world’s population ________ in cities rather than in the country.
| A．are living | B．will be living |
| C．have lived | D．will have lived |
It is because people are likely to stay indoors ______ the virus can spread easily ______ people often catch colds.
| A．and, that | B．so, that | C．therefore, so | D．that, that |
He gave us a nod and muttered a “yes” after _______ seemed like hours.
| A．that | B．which | C．it | D．what |
In any case, parents should make clear _______, if any thing, the children are expected to pay for with the money.
| A．that | B．which | C．what | D．how |