题目内容
Karaoke is very ______ (popular, possible) in big cities in China.
My students think taking part in sports is the most popular way of ______ (recitation, recreation).
It's very ______ (impossible, important) for us to fight pollution.
My father ______ (is used to, used to) go to work by bike.
Now the marathon ______ (takes place, happens) in many cities.