虽然望远镜具有较大的视觉放大倍率,但其横向放大倍率是视觉放大倍率的倒数,成缩小像
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开普勒望远镜物镜框为孔阑、目镜框为渐晕光阑,分划板为视场光阑
A. 对
B. 错
手持望远镜,由于考虑到望远镜视场抖动影响,通常设计到10倍以下较为合理
A. 对
B. 错
Read the following paragraph carefully and cross out the sentence which breaks unity.①The rapid increase in crime in Chicago is causing a great deal of concern to the city’s citizens. ②People are afraid to go out into the streets at night because they are afraid of being robbed or even killed. ③More and more families are moving out of the city into the suburbs because of the high crime rate. ④The chief of police was fired last month because of his inability to reduce crime. ⑤People are buying strong locks for their doors and installing heavy iron bars across their windows to prevent burglaries. ⑥Some citizens are even purchasing guns to protect themselves and their property. ⑦Indeed, it seems that the increase in crime is turning the average home in Chicago into a prison for its inhabitants.
A. ①
B. ②
C. ③
D. ④
E. ⑤
F. ⑥
G. ⑦
Read the following paragraph carefully and cross out the sentence which breaks unity.①The beaver has four gnawing incisors, two uppers and two lowers, that are rather ingeniously adapted to woodcutting. ②They grow constantly and wear with use to a chisel edge. ③The back side of the tooth, because it is made of a soft dentine, wears down, whereas the front side, outer-layered as it is with a very strong orange-colored enamel, doesn’t. ④The beaver has lips that can close behind the incisors to keep the mouth free of wood chips and, when the beaver is gnawing underwater, water. ⑤The beaver is the largest rodent in North America.
A. ①
B. ②
C. ③
D. ④
E. ⑤