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单选题
Chemical oxygen-generating systems require less space and weigh less than gaseous oxygen systems supplying the same number of people.
A
Gaseous oxygen systems have lighter weight and bigger size than chemical-generating systems when supplying air to the same number of people.
B
When providing oxygen to the same number of people, compared with the gaseous oxygen systems, chemical oxygen-generating systems need less space and have lighter weight.
C
Comparing with the chemical oxygen-generating systems when providing oxygen to the same amount of people, the gaseous oxygen systems are lighter and smaller.
答案解析
正确答案：B
