可否幫忙解釋一下:-

By general principle of cntract law, parties have to perform the promises they have made. When a contract has been performed, it comes to an end and is said to be discharged.

There are four ways that a contract may come to an end and be discharged if:
1. by performance
2. by agreement
3. by frustration
4. by breach

1. by performance
both parties must do precisely and ecactly what they promised. It can be answered only by looking at:
- the construction of the contract, to see what the parties promised to do, and
- the facts to see if what the parties have done corresponds with their promises.

2008-06-30 17:35:26 補充：
Further to 1. by performance, please also see below:

2. by agreement
a contract can be discharged if both parties agree. Can be anytime or under such situtation, written in the contract.

3. by frustration
When the external uncontrolable environment change, e.g. war

2008-06-30 17:35:34 補充：
4. by breach
not to performance. the Plaintiff can claim remedies.

Ref.: Vanessa Stott, An Introduction to Hong Kong Business Law