问题
选择题
据报道，某研究小组将二氧化碳与氢气按1：4体积比在一定温度、压强下混合并以铑一镁为催化剂可生成X，其反应为：CO2+4H2===X+2H2O，则X为 [ ]
A．CO
B．CH4
C．H2
D．C2H4
答案
答案：B
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据报道，某研究小组将二氧化碳与氢气按1：4体积比在一定温度、压强下混合并以铑一镁为催化剂可生成X，其反应为：CO2+4H2===X+2H2O，则X为 [ ]
A．CO
B．CH4
C．H2
D．C2H4
答案：B
It says that bats (蝙蝠) are almost blind (瞎的). Do you know _______ the bat finds the way? In fact (事实上), bats find their ways ______ the help of their ears. Bats make a ______ that we can’t hear at all. They cry when they fly and the echoes (回声) of these cries come back to their ______. In this way they can know where they should go. Bats fly out in the _______. In the daytime, they just stay together in their homes. When the evening comes, they begin to _______ and look for _______. The next morning, they come back from work to sleep _______ the evening. Some people _______ that bats are bad animals. In fact, they are very ______. They catch and eat pests (害虫). This is very good for people.
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