ICE 1 Two conditions are necessary for the formation of ice: the presence of water and temperatures below freezing. Ice in the atmosphere and on the ground can assume various forms, depending on the conditions under which water is converted to its solid state~ Ice that forms in the atmosphere can fall to the ground as snow, sleet, or hail. Snow is an assemblage of ice crystals in the form of flakes; sleet is a collection of frozen raindrops, which are actually ice pellets. Hail consists of rounded or jagged lumps of ice, often in layers like the intemal structure of an onion. Ice also forms directly on the ground or on bodies of water. In North America, ice forms in late autumn, winter, and early spring. On very large bodies of water, it may not form until late winter because there must be several months of low temperatures to chill such large amounts of water. 2 On puddles and small ponds, ice first freezes in a thin layer with definite crystal structure that becomes less apparent as the ice thickens. On lakes large enough to have waves, such as the Great Lakes, the first ice to form is a thin surface layer of slush, sometimes called grease ice, which eventually grows into small floes of pancake ice. If the lake is small enough or the weather cold enough, the floes may freeze together into a fairly solid sheet of pack ice. Pack ice may cover the entire lake or be restricted to areas near the shore. 3 Because water expands when it freezes, ice is less dense than liquid water and therefore floats rather than sinks in water. As ice floats on the surface of a lake, ocean, or river, it acts as an insulator and is thus important in maintaining the balance of the ecosystem. Without the insulating effect of floating ice sheets, surface water would lose heat more rapidly, and large bodies of water such as the Arctic Ocean and Hudson Bay might freeze up completely. Which statement is true about pancake ice
A. It forms on puddles and small ponds.
B. It falls from the atmosphere to the ground.
C. It may become a sheet of pack ice.
D. It is the least dense form of ic
The sensational news a couple of years ago that scientists had cloned a sheep sent academics and the public into a panic at the prospect that humans might be next. That is a (62) reaction. Cloning is a (63) challenge to the most fundamental laws of biology, (64) it is not unreasonable to be (65) that it might threaten human society and dignity. Yet much of the ethical opposition seems also to grow out of an unthinking disgust—sort of "yuck(令人厌恶的事物)factor. " And that makes it hard for even (66) scientists and ethicists to (67) the matter clearly. While human cloning might not offer great benefits to humanity, no one has yet made a persuasive (68) that it would do any real harm, (69) .Theologians (神学专家) (70) that to clone a human would (71) human dignity. That would surely be true if a cloned individual were treated as a (72) being, with fewer rights or lower (73) . But why suppose that cloned persons wouldn’t share the same rights and dignity as the rest of us A leading ethicist has suggested that cloning would violate the "right to genetic identity." (74) did he come up with such a right It makes perfect (75) to say that adult persons have a right not to be cloned without their voluntary, informed consent. But if such consent is given, whose "right" to genetic identity would be violatedMany of the science fiction scenarios(剧情) (76) by the prospect of human cloning turn out, (77) reflection, to be absurdly improbable. There is the fear, for instance, that parents might clone a child to have "spare parts" (78) the original child needs an organ (79) . But parents of (80) twins don’t view one child (81) an organ farm for the other. Why should cloned children’s parents be any different 75()
A. reason
B. sense
C. excuse
D. explanation