13. A lifebelt is the best thing for you to rowing.
划船时最好带着救生圈。
还能这样说：
You had better take a life ring with you to row.
The best thing you can take to row is a life buoy.
14. Chinese people are used to having a boat race on Dragon Boat Festival.
中国人习惯在端午节赛龙舟。
还能这样说：
It is a custom for Chinese people to have a boat race on Dragon Boat Festival.
Dragon Boat Festival is the day when people in China go to have boat races.
应用解析：
a race against time 和时间赛跑;
the rat race 激烈的竞争(尤指为保住职位或地位)
15. People who are seasick are not suitable to go boating.
晕船的人不适合划船。
还能这样说：
It is not appropriate for the people who are seasick to go boating.
Go boating doesn't suit the people who are seasick.