By now, when one makes a large purchase, he should have ___ opportunity to change his mind.
| A．accurate | B．urgent | C．special | D．adequate |
One in five humans ___access to safe drinking water by 2080．
| A．is said lacking | B．is said to lack |
| C．are said to lack | D．are said lacking |
It is hard to imagine what I ___today if I hadn’t been admitted to Nankai Middle School 15 years ago.
| A．would have done | B．will do |
| C．am doing | D．would be doing |
Not until they left school ___how much their teachers loved them and helped them．
| A．they realized | B．did they realize |
| C．they had realized | D．had they realized |
___three times in a row, the boxer decided to make a fourth attempt, though．
| A．Having defeated | B．To have defeated |
| C．Having been defeated | D．To defeat |
___is well known is that Africa had contacts with India and the Red Sea civilizations from the earliest times．
| A．As | B．It | C．What | D．That |