在( )里填上合适的数。
7+( )=15 ( )- 6=12
50+( )=52 13 -( )=8
( )+3=11 ( ) - 4=80
8;48;2;5;8;84
— If you want to protect your eyes from harm, which should NOT you do?
— _____ . [ ]
A. Wear sunglasses to protect your eyes from ultraviolet rays (紫外线)
B. Stay before the computer screen and play games for long
C. Do eye exercises every day
角膜屈光力占眼球总屈光力的( )
A.50%B.60%C.70%D.80%E.90%