Most environmental problem exist because___measures for preventing them were not taken in the past
| A．adequate |
| B．enough |
| C．many |
| D．much |
—Mr．Smith, I wonder if I could take Friday off?
—____? It's a bit difficult with so many people away on holiday, you know．
| A．How come | B．What about |
| C．Where are you going | D．Do you really have to |
He must have had an accident, or he ____ here for class then ．
| A．had to be | B．should be | C．would be | D．would have been |
Put yourself in situations where you will be forced to communicate in English, ____ you will see more progress over time．
| A．or | B．so | C．yet | D．and |
Thousands of people ____ the company stores to leave flowers, notes, even apples with
a bite in the past two weeks．
| A．had been attending | B．had attended |
| C．have been attending | D．attended |
Education is a lifelong process, ____ starting long before the start of schooling．
| A．which | B．that | C．it | D．one |