方程的两边同乘x（x-3），得
3x-9=2x，
解得x=9．
检验：把x=9代入x（x-3）=54≠0．
∴原方程的解为：x=9．
Tom likes _____ comedies, _____ Mike doesn't like _____ .[ ]
A. watch, but, ones
B. to watch, and. it
C. watching, but, them
D. watches, or, them
假设预热器C5落料温度为970℃，它属于（）信号.
A.AI
B.AO
C.DI
D.DO
