题目

 Miss Clarke works in a hospital .She is friendly to the patients and takes good care of them So they like her and most of them give her some presents when they are out of hospital.   It is Saturday .Miss Clarke doesn’t go to work .But she has to go outside the town to see a sick old woman .She gets on a bus and finds there are many people in it .She can’t find any seat. At  that moment an old man near  the door is going to stand up .The girl makes him back to his seat.   “Thank you ,sir “ says Miss Clarke .But please don’t do that .I’m able to stand .”But ,madam ,l下列命题中： （1）、平行于同一直线的两个平面平行； （2）、平行于同一平面的两个平面平行； （3）、垂直于同一直线的两直线平行； （4）、垂直于同一平面的两直线平行. 其中所有正确的命题有_____________。