单项选择题

According to the passage, uranium ore is very dangerous because______

A．it produces radioactive substances after it is dug out
B．it has caused deaths of many miners
C．the mining of it produces dangerous by-products
D．there is a problem in mining techniques
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单项选择题
Hot containers of nuclear wastes to be put in Antarctic region would______
A．remain above ice sheets
B．be safe to environment
C．be highly probable
D．remain under sea
单项选择题
It is implied in the passage that the primary difficulty in seeking a safe way to dispose of nuclear wastes is caused by______
A．the nuclear process involving the danger of radioactivity at its every stage
B．fuel for nuclear reactors producing dangerous wastes
C．the weakness scientists have found in every previous methods
D．the nature of nuclear wastes together with their lengthy life span
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