设f（x）在x=x₀处可导，且$\underset{△x\to 0}{\lim }\frac{f\left(x_0+3△x\right)-f\left(x_0\right)}{△x}=1$，则f′（x₀）等于（　　）

①近代中国落后挨打的屈辱史

②近代中国主动融入世界的开放史

③中国学习西方的思想解放史

④西方文明对近代中国发展的影响史

    Two magazines recently listed the best cities to live in. Here are two of the cities listed as "the world's best."

    SAN JOSE, COSTA RICA The city has comfortable weather all year round (15℃ to 26℃). Housing is not very expensive in San Jose. Also, many of the city's older neighborhoods are very beautiful and have small hotels and cafés. Beautiful mountains are around the city. Lots of people go sightseeing there every year. But air pollution is a problem in the city center.

    HONG KONG, CHINA This lively city—once a small fishing village—is today an international business center. It is an interesting mix of East and West, old and new. Modern tall buildings are next to small temples (庙宇). Popular nightclubs are close to traditional teahouses. Busy people fill the streets at all hours of the day. But outside the city, there are parks for walking or relaxing. Hong Kong is famous for its wonderful native dishes. There's also food from Europe, North America, and other parts of Asia. However, this small city has a large population of nearly seven million! That's why housing is often very expensive. Traffic and air pollution are also a problem.

暑假到了，我要去学游泳。我会（  ）去学游泳。