261.During the period from .. to .. , the output increased.

　　262.This is not a matter of the-earlier-the-better when we discuss sth.

　　263.It's difficult for them to cope with problems that others find easy to handle.

　　264.near-sightedness and stunted growth

　　265.sb should be on guard against sth.

　　266.Many people hold optimistic attitude towards... ,and are confident of the positive alterations it will bring to the present world.

　　267.transformation

　　268.People who believe in different religions may learn to give understanding to one another.

　　269.I hope you will place strong emphasis on living a healthy life in order to be truly happy.

　　270.The 'healthy' in question refers to being at the same time mentally and physically healthy.