锅炉按结构不同可分为火管锅炉和水管锅炉。( )

"Eyes are windows of the soul." Everyone knows the 36 of the eyes.  37 more and more students are becoming near-sighted(近视). So how to protect the eyes is still a serious problem. Here is some advice on 38 protect your eyesight(视力).
You should not keep your eyes 39 for a long time. When reading, you should keep the books about a foot away from you. After reading for an hour 40 two, you 'd better have a 41 by looking into the distance(远处).
You must remember not to read in dark light or in 42, not to read on a moving bus or in bed. Doing eye exercises will help 43 to protect your eyesight.
In a 44 , to keep 45 eyesight, we must have good studying habits.

小题1:A.importance	B. experience	C. difference
小题2:A. So	B. Because	C. But
小题3: A. what to	B. how to	C. when to
小题4: A. working	B. walking	C. waking
小题5:A. and	B. or	C. as
小题6:A. talk	B. rest	C. by
小题7:A. the earth	B. the star	C. the sun
小题8:A. him	B. us	C. you
小题9:A. word	B. sentence	C. letter
小题10: A. bad	B. good	C. weak