燃油锅炉灭火后,应关闭锅炉()和运行喷嘴的进回油阀,防止漏油。
A.炉前连通阀
B.烟风挡板
C.总油阀
D.给水阀
参考答案:D
温度计甲在空气中,温度计乙在密封的酒精瓶中,温度计丙在敞开的酒精瓶中,先发现他们的示数均是25°C,其中,有一个温度计不准确,由此可知( )
A.甲的刻度不准确
B.乙的刻度不准确
C.丙的刻度不准确
D.以上情况都有可能
In June of 1973, nine whales beached on the Florida coast. Beaching means swimming out of the ocean onto the beach, and usually dying there. No one knows why they do it, but a number of whales beach themselves every year. Some people think beaching is an accident. Perhaps the whales get confused. Scientists who studied the beaching of three dozen whales in Australia think the whales may have been confused by loud noises, Whales can tell where they are by sounds. They send out sounds and listen as they travel past or bounce off objects. Two days before these thirty-six whales beached, loud guns had been fired for two hours. The loud sounds may have confused the whales. Their confusion might have caused them to wander into low water. Whatever the reason whales beach, it is a sad event. People try to save them, but very few beached whales live. One whale that was rescued from beaching in Florida lived for forty-five days. That is the longest a beached whale has ever survived. And it lived that long only because it got attention from doctors. All over the world, scientists rush to whale beachings as soon as they hear about them. They hope to learn why whales beach, and how to save them.
The subject of this passage is ______.
A.the Florida Beaches
B.Beached Whales
C.Whale Sounds
D.Medical Treatment of Whales