A guest paying full fare can invite another guest to join the tour at half price.
A．支付全额费用的客人，每位可以再带一为客人参加旅游，按半价付费。
B．支付全额费用的客人，每位需要再邀请一位客人参加旅游，按半价收费。
C．每位按半价付费参加旅游的客人，必须再找到一位全额付费的客人参加。
D．支付全额费用的客人，如邀请另外一位客人参加旅游，可以退还一半费用。

A. not painted in a different color
B. not marked with bright tapes
C. fixed with grab bars
D. very brightly lit

A. are free from home accidents
B. can improve their health
C. are likely to live longer
D. can live more safely