问题
选择题
某人做酶的相关实验时，在试管中依次加入质量分数为3%的可溶性淀粉溶液2ml，2%的新鲜淀粉酶溶液2mL，放入适宜温度的热水中，保温5min。然后加入质量浓度为0.1g/mL的NaOH溶液1mL，摇匀，再加入质量浓度为0.01g/mL的CuSO4溶液4滴，摇匀，试管中液体的颜色是[ ]
A．无色
B．砖红色
C．蓝色
D．紫色
答案
答案：D
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某人做酶的相关实验时，在试管中依次加入质量分数为3%的可溶性淀粉溶液2ml，2%的新鲜淀粉酶溶液2mL，放入适宜温度的热水中，保温5min。然后加入质量浓度为0.1g/mL的NaOH溶液1mL，摇匀，再加入质量浓度为0.01g/mL的CuSO4溶液4滴，摇匀，试管中液体的颜色是[ ]
A．无色
B．砖红色
C．蓝色
D．紫色
答案：D
Do you know why different animals or pests(害虫) have their special colors? Colors in them seem to be mainly used to 1 themselves. Some birds like eating locusts(蝗虫), but birds cannot 2 catch them. Why? It is because locusts change their 3 with the change of the colors of crops. When crops are green, locusts look 4 . But as the harvest time comes, locusts change into the same brown color 5 crops have. Some other pests whose colors are 6 plants are easily found and eaten by 7 . So they have to hide themselves for lives and appear only 8 . If you 9 animals’ life, you’ll find the main use of colors is to protect 10 . Bears, lions and other animals 11 quietly through forests. They cannot be easily seen by hunters 12 their colors are much like the trees. Colors are useful not only on the land, but also in the 13 . A kind of fish can 14 a kind of black liquid(液体) when they face danger. The liquid spreads over quickly, so they cannot be found by their enemies and can quickly swim away. That is 15 they can live safely though they are not strong at all. So colors are really useful to animals.
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