Hip pop was first popular in the
A. 1980s
B. 1990s
New words and expressions. Study the words in the box and choose the right word for each blank.
根据科斯定理,一般来说,不管是由污染者还是受污染者负担降低污染的成本空气污染的数率最优水平是固定不变的。
A. 对
B. 错
Who are described in the recording?[音频]
A woman and a man in London.
B. Two young people in Tokyo.
C. Some American teenagers in New York City.
D. All of the above.
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