请问would 和 will应该怎么用?求例子.

would 是will 的过去式；表示过去将会发生的, eg: He wouldn't help me yesterday.would 也可以是情态动词,表示意愿,征求意见或者习惯, eg: Now that they know who I am,they wouldn't dare now. will 是将来时态, eg: I will do it. 第二人称疑问句中表示提出意见类的,will and would都可以用,would这时不是过去式. eg: Will/Would you please post the letter for me?