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问题 不定项选择题

下列说法不正确的是[ ]

A．高分子化合物材料一般具有固定的熔点

B．相对分子质量大的高分子一般具有热塑性，相对分子质量小的高分子一般具有热固性 C．高聚物的聚合度一般是不确定的

D．高分子化合物的溶解一般比较缓慢

答案

AB

填空题

Press Photographers


Good press photographers must have an "eye" for news, (26) journalists must have a "nose" for a good story. They must be able to interpret a story and decide rapidly how they can take (27) of the best opportunities to take pictures. The most difficult part of a press photographer’s job is that he or she has to be able to (28) a complicated situation with just one photograph. They rarely have second (29) and must be able to take the required (30) very quickly. Indeed, speed is essential — if the photographs are not (31) for the printing deadline, they are very unlikely to be of any (32) .
Most press photographers begin (33) with a local newspaper. There, the (34) is mostly for material of regional interest. Photographers may be expected to photograph a lot of unexciting events but to (35) the enthusiasm to put "something special" into every picture.
There is (36) competition among those who want to move from local to national newspapers. Here, the work is much more centered on news. The photographer must work (37) greater pressure and (38) more responsibility. Only (39) reliable, talented and resourceful photographers (40) this difficult move. The work is tough and can be (41) . On an overseas assignment, photographers may have to (42) unfamiliar food and accommodation, physical and mental stress, and (43) difficulty in transporting the pictures from an isolated area to get them to the newspaper (44) They also have to (45) the competition from other publications.

A. firmB. forceful C. strict D. p
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单项选择题

BC3皮带机三驱动的启动顺序为（）

A.1－2－3

B.2－1－3

C.3－2－1
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