地球大气层象保护伞一样保护着地球及地球上的生命。地球大气层存在的原因（ ）
| A．绿色植物光合作用的结果 |
| B．地球距离太阳远近适中 |
| C．太阳系中各天体的共同作用 |
| D．地球质量和体积适中 |
It has always been the _____ of our goverment to encourage graduates to start their business.
| A．plan | B．campaign | C．procedure | D．policy |
The most important _____ of his speech at the G20 summit was that we should all unite to fight against the finanical.
| A．element | B．spot | C．view | D．point |
He directed exposure to pigs,otherwise he_______pig flu.
| A．couldn’t get | B．wouldn’t have gotten | C．couldn’t have got | D．woud get |
In no time _______ me if he had any further information for pig flu..
| A．will he declare | B．he would notice | C．would he notify | D．he will note |
These plastic flowers look so _____ that many people think they are real,____they sell badly for the finanical crisis.
| A．beautiful,and | B．natural;while | C．artificial;though | D．real; so |