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British people now have more free time and holidays than they did twenty years ago. The (26) number of working hours has fallen, and by the mid-1980s almost all full-time manual employees were (27) to four weeks’ holiday or more, in addition to public holidays including (28) and Easter. The increasing number of unemployed, (29) the young, means that large (30) of the population have found themselves with more leisure time. Typical popular (31) in the UK include listening to pop music, going to a bar, playing and watching sports, going on holidays, enjoying outdoor activities, and watching TV. The number of people playing sports has risen, partly due to the (32) of more sporting (33) such as local leisure centers. (34) . Among the most popular sporting activities are walking, swimming, snooker and darts; fishing is the most popular country sport. Football, cricket, horse racing and motor sports are all popular spectator sports. (35) . Multi-screen cinemas have become more common and the number of people going to the cinema increased in the mid-1980s, after having fallen by more than a half between 1981 and 1984. (36) .

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某种铁线莲的根茎可作中药,有重要的经济价值。下表为不同遮光处理对其光合作用影响的结果,相关叙述正确的是( ) 遮光比例(%) 叶绿素a/b 叶绿素含量(mg/g) 净光合速率(μmol·m-2·s-1) 植株干重(g) 0 4.8 2.1 8.0 7.5 10 5.3 2.3 9.6 9.9 30 5.2 2.4 8.9 9.2 50 4.4 2.6 5.2 7.2 70 4.1 2.9 2.7 4.8 90 3.3 3.0 0 3.2

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B. 叶绿素含量与净光合速率成正相关
C. 遮光90%时,铁线莲不进行光合作用
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A. 6-巯基嘌呤
B. 氮杂丝氨酸
C. 别嘌呤醇
D. 甲氨蝶呤

设X服从参数为λ的泊松分布,PX=1=PX=2,则概率P0<X2<3=______.

袋中有8个球,其中有3个白球,5个黑球.现从中随意取出4个球,如果4个球中有2个白球2个黑球,试验停止,否则将4个球放回袋中重新抽取4个球,直至取到2个白球2个黑球为止.用X表示抽取次数,则PX=k=______(k=1,2,…),

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