如果线路上有人工作，应在( )上挂“禁止合闸，线路有人工作!”的标示牌。A．线路断路

新鲜尿液具有大蒜臭味，提示为（）

A.慢性尿潴留

B.慢性膀胱炎

C.有机磷中毒

D.酮症酸中毒

E.膀胱癌

—What can you do, Lin Tao?

—________. 　　 [ ]

A. I like sports

B. I want to join the music club 　　

C. I am well

D. I can do Chinese Kung Fu

Generally,in order to be preserved in the fossil record, organisms must possess hard body parts such as shells or bones.Soft,fleshy structures are quickly destroyed by predators pr decayed by bacteria. Even hard parts left on the surface for and length of time will be destroyed Therefore, organisms must be buried rapidly to escape destruction by the elements and to be protected (5) agents of weathering and erosion Marine organisms thus are better candidates for fossilization than those living on the land because the ocean is typically the site of sedimentation, whereas the land is largely the site of erosion.The beds of ancient lakes were also excellent sites for rapid burial of skeletal remains of freshwater organisms and skeletons of other animals, including those of early humans Ancient (10)swamps were particularly plentiful with prolific growths of vegetation, which fossilized in abundance.Many animals became trapped in bogs overgrown by vegetation.The environment of the swamps kept bacterial decay to a minimum, which greatly (aide(D)in the preservation of plants and animals.The rapidly accumulating sediments in flood plains, deltas, and stream channels buried freshwater organisms,along with other plants and animals that happened to fall into the (15) water. Only a small fraction of all the organisms that have ever lived are preserved as fossils.Normally, the remains of a plant or animal are completely destroyed through predation and decay.Although it seems that fossilization is common for some organisms, for others it is almost impossible. For the most part, the remains of organisms are recycled in the earth, which is fortunate because (20) otherwise soil and water would soon become depieted of essential nutrients. Also, most of the fossils exposed on Earth’s surface are destroyed by weathering processes.This makes for an incomplete fossil record with poor or no representation of certain species.The best fossils are those composed of unaltered remains. Generally, it is the inorganic hard parts, composed mostly of calcium carbonate, that form the vast majority of unaltered fossils.Calcite and (25) aragonite also contributed to a substantial number of fossils of certain organisms.

The fact that the "land is largely the site of erosion" (line 7) is significant because ().

A．erosion is less destructive than sedimentation

B．fossils are most common in areas Subject to erosion

C．erosion contributes to the destruction of skeletal remains

D．few organisms live in areas that experience extensive erosion

用比色法鉴定黏土中的有机物含量时，应浅于标准色。( )