这是新教材高二英语上学期 的全部的语言点 Unit 10
Useful expressions：
1) on board 在船（飞机，车）上，上船（飞机，车）在句中可以作为副词，后置形容词或者介词。
As soon as they went on board , the plane took off.（作状语）
他们一登上飞机，飞机就起飞了。
There were 50 people on board when the ship sank.（作定语）
船下沉的时候有五十个人在船上。
More people are on board the bus from downtown to the countryside on holidays.（介词）
假期有更多的人乘这辆车从市中心到乡村去。
2) at hand 随身，附近；即将发生
I always have a dictionary at hand while reading.
阅读时我手边总放着一本字典。
The final exam is at hand. 大考快要到了。
