6. Many died or returned home, but most remained in California to make a life for themselves in the new towns or on farms.

1). remained:系动词,"留下","逗留".

I'll remain to see the end of the game.

The foreign guests remained in Beijing for two weeks.

2) make a life: to change the way one is living

make a living: to do work to earn money

7. It was the building of the railway from the west to the east coast that brought even larger numbers to California in the 1860s.

这是强调式句

8....... which today still keeps up its Danish culture.

keep up: never stop,continue steadily,go on

The manager asked the workers to keep up the work.

The rain kept up for two days and the roads were flooded.

9. People from Africa have been living in California since the 1800s, when they moved north from Mexico.

have been doing 现在完成进行时,强调始于过去某时的动作持续发生到现在.

eg He has been painting the room. 他一直都在粉刷房间.

when they moved north from Mexico

这是一个非限制性定语从句，对先行词"the 1800s" 进行补充说明，先行词在从句中作时间状语，因此用关系副词"when"引导。

10. California has become home to people from Asia, including Cambodians,Koreans, Vietnamese and Laotians.

become home to:成为家园

The island has become home to snakes.

occur: 1)come into sb's mind (想起，想到) When did the accident occur?

2)happen, take place(发生) A good idea occurred to me all at once.

11.multi-前缀，是"多，多方面，多方向"的意思

思维拓展：

mono-前缀：one, single 单

eg: a monolingual dictionary(单语词典) monoplane(单翼机)

bi-前缀：two, twice, double双

eg: a bilingual dictionary(双语词典) bicycel (自行车)

12.declare v.宣告，声称，宣称，申报

1) to make known publicly or officially 宣告，公告 War was declared on the enemy.