| 下列方程中，一元一次方程的有（ ）个 （1）2x-3y=6；（2）x2-5x+6=0；（3）3（x-2）=1-2x；（4）
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（1）含有两个未知数，故不是一元一次方程；
（2）未知数的次数是2而不是1，故不是一元一次方程；
（3）符合一元一次方程的定义；
（4）不是整式方程，故不是一元一次方程；
（5）不是等式，不是方程．
综上可知：只有（3）正确．
故本题选A．
It was Sunday afternoon. My brother and I were alone at home. My parents went for a party and asked me to look after my brother. I was doing my homework while my younger brother was watching TV. Suddenly the doorbell rang. Ding-Dong! My brother thought that it was our parents, so he opened the ________soon. A tall man wearing a black raincoat stood outside. He said that he came to sell books and asked politely__________ our parents were at home. Without thinking, my brother said,“No.” Then the man asked if we would like to ______some story books. I refused him. When I wanted to close the door, he suddenly pushed the door very _______and came into our house. He took out a ________and ordered me to tie up my brother’s hands with a rope. I tied up his hands in a special way so my brother could untie ______easily. The man then tied my hands up and locked _______of us in the kitchen. Soon, he went upstairs to _________money. I taught my brother to untie the rope on his ______. He then untied me. I rushed to the telephone to call the police, ______the line was dead. The doors were all locked from the outside. It was lucky that the man ______to lock the kitchen window. We got out of the house through the kitchen window and went to the _______ pay phone to call the police Soon _______came to our house and the man was caught. By that time, my parents had come home. We told them the whole story. My parents were ______that we were not hurt. They told me that I should stop my brother from _______the door to strangers. I learned a lesson on safety.
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