题目

下列各式变形错误的是（ ）A. 变形为 B. ，变形为C. ，变形为 D. ，变形为 答案：【答案】D【解析】根据等式的性质对各选项分析判断后即可解答．选项A，变形为，正确；选项B，，变形为，正确；选项C，，变形为，正确；选项D，因为，变形为，所以选项D错误.故选D.It was not long _____ he was born that his mother died of illness.A．beforeB．whenC．thatD．after