酒精的热值是3.0×107 J/kg，完全燃烧2kg酒精能放出热量____ J；若将一杯酒精的质量倒掉一半，则剩下的酒精热值为____ J/kg。
观察漫画，回答问题：
—My parents don't want me to watch TV on school nights. What should I do?
—Well, you _________ talk with them, but you must finish your homework first.
若|m﹣2|+|n+3|=0，求m+n的值．
