第三部分 LANGUAGE POINTS

1 Without it we could not make a living. 
Without it 是非正式条件句的作用,所以主句用could not
make a living  谋生

2 Sometimes were go upstream to a favourite backwater, sometimes we have our party at the boathouse, which a predecessor of ours at the farm built in the meadow hard by the deepest pool for swimming and diving.
两个Sometimes 后面是两个并列关系的主句,它们由"逗号"连接, 这种现象较少见. 一般在逗号后加上连词"and"
which the boathouse 引导定从

3 We welcome the seasons by the riverside, crowning the youngest girl with flowers in the spring, holding a summer festival on Midsummer Eve, giving thanks for the harvest in the autumn, and throwing a holy wreath into the current in the winter.
这个句中有三个分词短语组成的并列状语.它们是crowning ...giving... throwing... , 它们都是表伴随状态

4 We are lucky in that only the lower fields, which make up a very small proportion of our farm, are effected by flooding, but other farms are less favorably sited, and flooding can sometimes spell disaster for their owners.
这句有三个主句,其中连词 but 之前的句子和后两个是让步转折的关系,连词 and连接后两个并列关系的句子
spell...  for somebody 新概念英语学习方法