已知直线l：y=-x+1，现有下列3个命题：其中，真命题为①点P（2，-1）在直线l上②若直线l与x轴，y轴分别交于A，B两点，则AB=2；③若a＜-1，且点M（-1，2），N（a，b）都在直线l上，

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已知直线l：y=-x+1，现有下列3个命题：其中，真命题为（　　）
①点P（2，-1）在直线l上
②若直线l与x轴，y轴分别交于A，B两点，则AB=2；
③若a＜-1，且点M（-1，2），N（a，b）都在直线l上，则b＞2．

A：①②

B：②③

C：①②③

D：①③

上一题下一题 0.0难度选择题更新时间:2010-05-07 09:54:06

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C

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