How has the Constitution of the United States been able to stay relevant and
effective as a government for over 200 years?

The Constitution has survived for so long largely for two reasons. ... As a previous educator has pointed out, the Constitution has only been amended 27 times in all. This is no accident. The framers of the Constitution feared radical change and so wanted to make it as difficult as possible to make amendments.

Explanation:

anticipatory breach of contract

as the name suggests, an anticipatory breach is a breach of contract before the time of performance. so, if a promisor denies to perform his promise and signifies his unwillingness before the time for performance, then it is an anticipatory breach of contract.

and

actual breach of contract

while an anticipatory breach is before the time of performance, an actual breach of contract is on the scheduled time of performance of the contract. an actual breach of contract can be committed either.

hope this . : )