This is a farm.It is____and warm today.I can see a____and her three children,three____,two____,a____and a____on the farm.There is a____on the left.Behind the farm there are three high____.In the sky there are____and ____.
— I find it difficult to learn Physics well.
— That's true. Nobody can learn it well _______ he works hard at it.
第三世界以独立的力量登上国际政治舞台的事件是( )