求证：三角形的中位线平行于三角形的第三边，且等于第三边的一半．

一个南瓜所受的重力为60N，它的质量为 ____ kg ．月球的引力只是地球的 ，那么该南瓜在月球上受到重力为 ____ N．（g取10N/kg）

    There is a woman ____（name）Daisy who has devoted all her life to ____（attend）to the homeless children. It's generally recognized that what she has done for children ____（deserve）to be respected by everyone. ____（personal）speaking, her selfless behavior sets a good example to us.

    There was a time when I came across Daisy who ____（invite）to deliver a speech, during which she indicated, “____（take）care of homeless children is just ____ ordinary job, but it doesn't mean that you can look down ____it. Every job is equal. We can't say which one is ____（good ）.” She also said, “Once you set out to do something, you ought to carry on with it to the end, ____ you will gain nothing in the end.”