Điền từ thích hợp

in Britain a hundred years ago, only very rich people could go on holiday. Travelling was very expensive, and most people
didn't have (17) money to go away and stay in (18) hotel.
In the 1960s, holiday camps near the sea (19)
popular. They didn't cost much, and people didn't need to travel very
far to enjoy a week of fun by the sea.
By the 1980s, it was much cheaper to fly than ever before. A lot of people were able to travel to (20) countries for the
first time for (21) holidays. For British people, a week on the beach is still the most popular type of holiday.
17.A enough(giải thích)
18.C a(giải thích)
19.A became(giải thích)
20.B others(giải thích)
21.C their(giải thích)