Which offer cannot be revoked?

中国大学MOOC: Which offer cannot be revoked?

中国大学MOOC: An acceptance can be revoked after it becomes effective.

An acceptance can be revoked after it becomes effective. A: 正确 B: 错误

中国大学MOOC: The authorities have revoked their original decision to allow development of this rural area.

When will an offer become effective? A: when it is dispatched B: when it reaches the offeree C: when it is withdrawn D: when it is revoked

A stand-by letter of credit ______________. A: is never revoked B: is not a letter of credit C: is invoked in the event of non-compliance by buyer or seller with the terms of an original credit D: is invoked in the event of non-compliance by the buyer or seller with the terms of the sales contract