Would is an interesting modal with numerous functions. For example, it is used to make polite offers or requests: Would you like some more tea? or Would you help me please? It is often used to express wishes: I wish you wouldn't keep tapping your pencil on the table. It is frequently found in indirect speech as in the following: She said she would call you as soon as she got back. And it is very common in conditional sentences such as I would go if I had the time or She wouldn't have been so angry if you had asked her first.
But would also has its own special problems. Look at the following sentences and decide first whether the sentence is possible or not. If it is possible, say what it means; and if it is not possible, express the meaning in correct English.
In this sentence would has the meaning of used to.
We saw in the previous sentence that would often has the meaning of used to. However, it cannot be used in this way with the verb to have when have means to possess. It must be: When I was a child I had (or used to have) a lot of wonderful toys.
Here would (not) means refused - He refused to stop.
Here would means was willing to.
In the previous sentence would clean my room referred to a general willingness in the past to do something. However, would cannot be used in this way when referring to a single event in the past, so I would clean my room yesterday is not possible! It has to be: I was willing to (or didn't refuse to) clean my room yesterday.
Just to make matters more confusing, it IS permissible to use would when referring to a single past unwillingness. Another example: He begged and begged, but I wouldn't tell him my secret.
Would is very common in conditional 2 sentences (but see below!)
It is not standard English to use would in the if clause of a conditional sentence. You have to say If I were (was) rich ..
In this sentence would has the function of expressing annoyance. It can be paraphrased: Why did you (have to) tell him about the present ..?
This sentence means: I wish that I were rich!