［B］ It cannot be fully restored once damaged.       ［D］ There are various ways to protect it.

    27.     ［A］ It may make the wearer feel tired. ［C］ It can lead to the loss of vision in children.

    ［B］ It will gradually weaken the eyes of adults.     ［D］ It can permanently change the eye structure.

    28.     ［A］ It can never be done even with high technology. ［C］ It is a major achievement in eye surgery.

    ［B］ It is the best way to restore damaged eyesight.       ［D］ It can only be partly accomplished now.

    Passage Two

    Questions 29 to 31 are based on the passage you hav