21.  But by 1990 with the development of economy in many developing countries, people's living level had been improved greatly.

22.  Second, the medical facility also improved to a high level.

23.  So high level medical facility can protest people's healthy .

24.  Withe the rapid improvement of science, people's healthy can reach a very high level.

25.  First, there was a high progress in people's living level in developing coutries .

26.  Secondly, the living level has been increased much in the past thirty years.

27.  the level of people's living went up.

28.  After 1960 life level was improved rapidly.

29.  Their technology level is lower .

30.  Firstly, in recent years, the economy has developed quickly, The people's life level of these countries is better than before.