在下面对话的空格内填上一个适当的词，使对话意思完整，语句正确。
A: Huang Hai, why do you look so tired and worried today?
B: I got up very early this morning as my family has moved to a new building. The new flat (套间) is much
1. than the old one.
A: Congratulations! You've moved to a new flat!
B: Thanks. But it's about ten kilometres from my new house to the school. It takes me a longer time to go to
school. The population of Guangzhou is 2. very fast, you see. But there is not enough space for us
to build new buildings in the city centre. Most of the new buildings have to be built in the places 3.
away from the city centre.
A: I quite 4. with you. And people spend more money and more time on their way to work.
B: What's more, the traffic will be heavier and the air will be 5. because there are more and more buses
and cars. So the population problem may be one of the serious problems of the world today.