EXPRESSING AGREEMENT AND DISSAGREEMENT

In real life, you definitely often asks wheter one agrees or disagrees with what you
are doing or you select. Here are some sayings that can be used to express approval or disapproval:

A. AGREEMENT
- I agree (saya setuju)
- I am with you (saya sependapat dengan anda)
- I think so (saya kira begitu)
- That's what I was thinking (itulah yang saya pikirkan)

B. DISAGREEMENT
- I disagree (saya tidak setuju)
- I am not with you (saya tidak sependapat dengan anda)

Constructive disagreement
1. I can appreciate your point about..., but I would disagree because...
2. I am not so sure about that because...
3. I don't think that's the case because...

Source :

http://education-co.blogspot.com/2012/11/expressing-agreementdisagreement.html 

http://nadiirrss.blogspot.com/2014/02/expressing-agreement-and-diasagreement.html