4. People begin to know that most environmental problems exist because necessary measures for preventing them _______taken in the past.
| A．are not | B．were not | C．hadn't been | D．wouldn't be |
As we all know, ______ medical examination will help us find out health problems as early as possible.
| A．common | B．general | C．regular | D．normal |
Since the beginning of the vacation，I across the country，and my next stop is the Wuyi Mountains．
| A．had traveled | B．will travel | C．have been traveling | D．was traveling |
Once again he didn’t hand in his homework _____ he had been given enough time to do it．
| A．in case | B．as though | C．so that | D．even though |
The Hotel Al Arab ______ the first and only 7-star hotel in the world was designed in the shape of a sail of 321 meters.
| A．was considered | B．considering | C．being considered | D．considered |
The conference aims to develop business and let people think about ______ they can have a
positive influence on the planet．
| A．why | B．that | C．what | D．how |