下列等式中，是一元一次方程的有（ ） ①2006+4x=2008；②3x－2x=100；③2x+6y=15；④3x2－5x+26=0
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答案：B
答案应选B
只含有一个未知数（元），并且未知数的最高次数是1（次）的方程叫做一元一次方程．它的一般形式是ax+b=0（a，b是常数且a≠0）．
解答：解：①符合一元一次方程的定义；
②化简后为x=100，符合一元一次方程的定义；
③含有两个未知数，不是一元一次方程；
④含有一个未知数，并且未知数的最高次数是2，不是一元一次方程．
故选B．
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| I just returned from a twoweek tour of Europe. On my teacher's salary, I could_1_afford to travel there with Western tours, _2_I decided to go travelling with a Chinese tour. Besides the affordability, the truth is that I am a_3_traveller. Making all the reservations and connections is a nightmare for me, so I am_4_to sacrifice autonomy(自主权)_5_security. This does, however, _6_that one should always follow its leader. In most aspects of my life, I am extremely_7_. No one carries my purse and parcels. I have gone bravely into wildly different life changes, _8_when it comes to_9_, show me a flag and I'll follow it. The group leaders were a bit nervous at first. But I promised them that my not speaking Chinese was not a problem. I'd just go 10 they pointed. There was one little 11 however. I wouldn't be eating Chinese food with them. I would find an eatery(小餐馆) nearby and enjoy local cuisine. It worked out fine. Since I was single, I usually 12 a room with another woman. On my first trip, to Egypt, I couldn't have been 13 . They paired me up with Shelley, who 14 fluent English and we adored each other almost instantly. The second time, my potential roommate took one look at me and said she'd rather sleep with her friends on a rollaway in 15 room. I was 16 at first, but then realised I'd have a room to myself, so why got upset? Travelling in a group meant that the first day we were all 17 , but we got familiar 18 each other on the bus and 19 each other's faces quickly in a crowd. We got 20 comfortable with each other and soon a family atmosphere developed. | ||||
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