一篇发表于1941年题为《三十年来的中国农村》的文章，包括五个主要部分：（一）农产商品化的加速。（二）纯封建制渐归消灭。（三）高利贷制变本厉。（四）地权集中、农民离散。（五）劳力锐减、熟荒骤增。可以看出该文的主线是（    ）

阅读下面短文，在空白处填入一个适当的词，或填入括号中所给单词的正确形式。

    Everyone has his own way of saying things and his own special expressions. Many everyday American expressions are based ____ colors. Red is a hot color. Americans often use ____to express heat. They may say they are red hot about something unfair. When they are red hot they are very ____(anger) about something. The small hot tasting peppers found in many Mexican foods ____(call) red hots for their color and their spicy taste. Fast loud music is popular with many people. They may say the music is red hot,____ (especial) the kind called Dixieland jazz. Pink is a ____(light) kind of red. People sometimes say they are in the pink ____they are in good health. The expression was first used in America at the beginning of the ____(twenty) century. It probably comes from the fact that many babies are born with a nice pink color ____shows that they are in good health. Blue is a cool color. The traditional blues music in the United States is ____opposite of red hot music. Blues is slow, sad and soulful(深情的). Someone who is blue is very sad.