听长对话，选择正确答案

两根同样长的钢筋，其中一根锯成3段用了12分钟，另一根要锯成6段，需要24分钟。

如果命题“非或非”是假命题，则在下列各结论中正确的是      （    ）        
①命题“且”是真命题；         ②命题“且”是假命题；
③命题“或”是真命题；         ④命题“或”是假命题。

短文改错。便条中共有10处错误,每句中最多有两处。错误涉及一个单词的增加、删除或修改。
增加：在缺词处加一个漏字符号（∧）。并在其下面写出修改后的词。
删除：把多余的词用斜线（＼）划掉。
修改：在错的词后划一横线,并在该词下面写出修改后的词。
注意：1）．每处错误及修改均仅限一词;
2）．只允许修改10处,多者（从第11处起）不记分。
    One day, I was cooking in the kitchen when the telephone rings. I went to answer it immediately. She was my close friend, Lisa. When we were talking on a phone, the fire alarm sounded. I dashed back to the kitchen. The room full of smoke and the beef was bad burnt. I quickly turned off the gas, opening all the windows, and then rushed out of the house. In my surprise, two fire engines were outside my house. I was rather worrying. I told about the firemen that it was my careless cooking which caused the heavy smoke.

在现代市场经济中，资源配置主要依靠（  ）来实现。