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问题 选择题

实验室用过氧化氢（二氧化锰，作催化剂）制取氧气，下列仪器一定不需要的是（　　）

A．大试管

B．铁架台

C．酒精灯

D．水槽

答案

因为实验室用过氧化氢（二氧化锰，作催化剂）制取氧气，是“液+固→常温”型制取装置，所以不需要加热．故不需要加热装置：酒精灯．

故选C．

选择题
Remembering _______, he is really not sure whether he can make it this time.

A. his all past unpleasant terribly experience
B. his past all terribly unpleasant experience
C. all his past terribly unpleasant experiences
D. all his terribly unpleasant past experiences
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单项选择题

Even plants can run a fever, especially when they are under attack by insects or disease. But (1) humans, plants can have their temperature (2) from 3,000 feet away—straight up. A decade ago, (3) the infrared scanning technology developed for military purpose and other satellites, physicist Stephen Paley (4) a quick way to take the temperature of crops to determine (5) ones are under stress. The goal was to let farmer (6) target pesticide spraying (7) rain poison on a whole field, which (8) include plants that don’t have the pest problem.

Even better, Paley’s Remote Scanning Services Company could detect crop problem before they became (9) to the eye. Mounted on a plane flown at 3,000 feet (10) , an infrared scanner measured the heat emitted by crops. The data were (11) into a color-coded map showing (12) plants were running "fevers". Farmers could then spot spray, using 50 to 70 percent less pesticide than they (13) would.

The bad news is that Paley’s company closed down in 1984, after only three years. Farmers (14) the new technology and long-term backers were hard (15) . But with the renewed concern about pesticides on produce, and refinements in infrared scanning, Paley hopes to (16) into operation. Agriculture experts have no doubt about the technology works. "This technique can be used (17) 75 percent of agricultural land in the United States," says George Oerther of Texas A＆M. Ray Jackson, who recently retired from the Department of Agriculture, thinks (18) infrared crop scanning could be adopted by the end of the decade. But (19) Paley finds the financial backing (20) he failed to obtain 10 years ago.

18（）

A.remote

B.lonely

C.removed

D.desolate
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