题干
写出短文中所缺的单词。(每空一词)
In the future I am going to be an inventor．This winter holiday I don't want to go out to play．I want to ____something myself at home．I want to help old people____a light and folding bike．They ride it to the ____，then folding it and put it in the bag．After buying some things they can ride it and carry their things to go ____．They are not tired．I think if they see it，they must be very ____．
答案(点此获取答案解析）
Invent,Make,Market,Home,Happy
是两条不同的直线，
是两个不同的平面，有下列命题：
，则
； ②若
；
； ④若
，则
；
是 （ ）