人体呼出的气体比清新的空气含有较少的（    ）。                                                                                                                                                                                        

A、氧气       B、氮气        C、二氧化碳       D、水蒸气

人体呼出的气体比清新的空气含有较少的

1. A.
   氧气
2. B.
   氮气
3. C.
   二氧化碳
4. D.
   水汽

人体呼出的气体比清新的空气含有较少的                                                                                                                                                                                       

A. 氧气       B. 氮气        C. 二氧化碳       D. 水蒸气

人体呼出的气体比清新的空气含有较少的（   ）。                                                                                                                                                                                       

人体呼出的气体比清新的空气含有较少的

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