基本信息
Unit 15 Popular youth culture
具体内容：
1. On the annual International Volunteers Day, the world acknowledges the work of millions of people who give their time to help others.
on : at specific time of
e.g.
They arrived on the morning of July 1st.
She was rushed to hospital but was dead on arrival.
The bus starts on the hour, i.e. every hour exactly.
2. I really feel I am doing something worthwhile and I am having a great time doing it.
worthwhile: adj. deserving the effort needed, the time or money spent
worth perp.
worthy adj.
e.g.
It’s worth much more than I paid for it.
It isn’t worth waiting for him.
The performance is worthy to be remembered.
We had a long wait, but it was worthwhile because we got the tickets.
Have a great time（in）doing it.
3. Coming to another country to study requires a big adjustment and it takes a while to fit in.
4. although the styles may change from year to year, jeans never go completely out of fashion.
out of / in fashion: considered/ not very modern now
After a fashion: although not very well
e.g.
