Ⅰ. agree to “同意、应允”通常用于同意某件事情（我们可以同意我们自己有不同看法而并不赞同的事情）。
如：
① Do you agree to this plan?
② He agreed to my proposal.他同意了我的提议。
③ I agreed to his terms. 我同意了他的条件。
Ⅱ. agree with “同意、赞同”常常表示同某人意见一致，也可表赞同某件事情。还有“（气候、食物等）适合”之意。
如：
① I quite agree with you.我很同意你。
② Do you agree with me ?
③ I agree with all you say.我同意你所说的。
④ His words do not agree with his actions.他言行不一致。
⑤ Too much meat doesn’t agree with her.吃太多肉对她身体不合适。
[注]：agree with 不能用于被动语态。
Ⅲ. agree on /upon “对……取得一致意见”指两方或多方就某个问题取得了一致的意见或达成了某种协议。
如：
① After discussion the two sides agreed on a cease-fire. 经过讨论，双方就停火问题达成了协议。
② They all agree on the plan.他们对这个计划意见一致。
[注]：此句型可转换成agree in doing sth.如：
① All of them agreed on / upon it. = All of them agreed in doing it. 他们对做这个问题达成了共识。
