题目

 The calculations, had they been done by hand,        all practical value by the time they were finished. A. had lost                                               B. would lose       C. should have lost                                   D. would have lost 答案：D睢宁是意杨之乡，意杨林是一巨大的天然“氧吧”，因为绿色植物在光合作用下可以放出大量的氧气（有资料表明绿色植物在光合作用下每吸收l03J的太阳能可以放出0.05L的氧气）．小明同学为测量地球表面植物吸收太阳能的本领，做了如下实验：用一脸盆装6kg的水，水面的表面积为0.1m2，经太阳垂直照射l5min，温度升高了1℃．[水的比热容是4.2×103J/（kg?℃）]．求：（1）实验时6kg的水吸收了多少热量？（2）若地表植物接收太阳能的能力与水相同，那么l00m2绿地15min可以放出多少升的氧气？