why are we always tired, do you know? Firstly if we cant sleep w 1 ,we will be tired.But we are often too b 2 .we cant f 3 our work in the day and we must do it at n 4 .we go to bed l 5 and get up e 6 .so we cant sleep well.Most people need at 1east eight hours and some more.If we sleep for only five or six hours a night, we will be tired.Secondly, when we are ill we will be t 7 .But we dont know we are ill.so if you are always tired, perhaps you are not so h 8 .Youd better go to see a doctor.Thirdly, perhaps you cant eat some kinds of food like eggs, nuts, meat, chocolate or coffee.If you are ill and tired after eating some food, please dont eat it a 9 longer.But please eat more if you are well.At last, if the air around you isnt nice and clean，you will feel tired.So please open your w 10 often or go out for a walk and you will feel better.
参考答案：
1.well 2.busy 3.finish 4.night 5.1ate 6.early 7.tired 8.healthy 9.any 10.window/windows