Using Agreement And Disagreement

1.   To Agree

• Nod your head "yes," and murmur "Mmmhmm." This is the simplest way to acknowledge what someone says and that you agree in English 
• Wait until is your turn to speak, and use expressions such as "I agree with. . .," "I think. . .is a good idea," and "I think you're right." 
• Begin by agreeing with what another person has said, but add a qualifier if you do not completely agree. For example, say "I agree with you, but. . ."; "That makes sense; however. . ."; or "It's a good idea, but. . ." (See Reference 2.) If you agree with everything that the other person says, you can say, "I completely agree," or "You're totally correct/right."

2.   To Disagree

• Remain calm. Keep any anger or disrespect in check. Calmly express your disagreement, all the while respecting the other person's opinions. 
• Use phrases such as "I disagree because. . ."; "The problem with that is. . ."; "The way I see it. . ."; "I'm against it because. . ."; "Instead, I think that. . . 
• Say "I'm afraid. . ." before you finish your disagreement statement. For example, you could say "I'm afraid I don't agree with you," or "I'm afraid I can't agree." If you do not agree with anything the other person has said, you can say, "I am afraid I completely disagree with you."This are examples of how to remain polite in expressing your disagreement in English. (See Reference 3. 
• Notice that when you disagree with someone in English, you need to give a reason why you disagree. It is not enough to simply state that you think the other person is wrong and leave it at that. Explain your thoughts and opinions fully 
• Offer solutions when you disagree as well. You may not like the other person's way of looking at a situation, but, unless you can come up with a better idea, it may be better to not say anything at all. Use phrases such as "I think we should. . ."; "We could. . ."; "One solution may be. . ." (See Reference 2.)

Notice that these phrases use words like "should" and "could" that indicate that there may be other solutions that are equally feasible and acceptable. This is another example of how English speakers generally try not to speak so forthrightly and assert that their opinion is the only one that is correct.