英语阅读理解（根据短文回答问题）

英语阅读理解（根据短文回答问题）
短文：We spent a day in the country and picked a lot of flowers.Our car was full of flowers inside!On the way home we had to stop at traffic lights,and there my wife saw the bookshelf.
It stood outside a furniture shop.“Buy it,” she said at once.“We’ll carry it home on the roof-rack（车顶架）.I’ve always wanted one like that.”
What could I do?Ten minutes later I was twenty dollars poorer,and the bookshelf was tied on to the roof rack.It was tall and narrow,quite heavy too.
As it was getting darker,I drove slowly.Other drivers seemed more polite than usual that evening.The police even stopped traffic to let us through.Carrying furniture was a good idea.
After a time my wife said,“There’s a long line of cars behind.Why don’t they overtake（超车）?”
Just at that time a police car did overtake.The two officers（警官）inside looked at us seriously when they went past.But then,with a kind smile they asked us to follow their car through the busy traffic.The police car stopped at our village church（教堂）.One of the officers came to me.
“Right,sir,” he said.“Do you need any more help now?”
I didn’t quite understand.“Thanks,officer,” I said.“You’ve been very kind.I live just down the road.”
He was looking at our things:first at the flowers,then at the bookshelf.“Well,well,” he said and laughed.“It’s a bookshelf you’ve got there!We thought it was--er,something else.”
My wife began to laugh.Suddenly I understood why the police drove here.I smiled at the officer.“Yes,it’s a bookshelf,but thanks again.” I drove home as fast as I could.
1.The car was full of flowers ,wasn't it?
2.What made the writer think that carrying furniture was "a good idea"?
3.Why were the police and other drivers so kind to the writer?
4.Why did the writer's wife begin to laugh?
5.When did the offices begin to realize they had made a mistake?
6.Did the writer understand what happened at first?