题目

O2F2可以发生反应H2S＋4O2F2===SF6＋2HF＋4O2，下列说法正确的是( ) A．氧气是氧化产物                                           B．O2F2既是氧化剂，又是还原剂 C．若生成2.24L HF，则转移0.4mol电子      D．还原剂与氧化剂的物质的量之比为1∶4 答案：DIt is said that the software on learning subjects for pupils       in a very practical way. A. designed              B. designing              C. are designed                D. is designed