Many of these sentences are incorrect, sorry. I'll give correct examples and try to explain them: I agree with the new policy. They agreed upon a new policy. (ie. from negotiation... "I" is not possible) I disagree with the new policy They disagree on the new policy. (on = regarding) "Agree" is a verb, so yes "I agree with you" is correct. None of the "waiting" sentences are correct. You need: I have been waiting for you since morning. He is going to visit the USA in July. (July represents a period of time - adding the year doesn't change that.) But... He is going to visit the USA on July 12, 2012. (Here we have a date: use "on") Please, I need some expert advice. (Advice is an uncountable noun, so you don't use "a". "Advise" is the verb.)

I agree with the new policy. = I am for the new policy. Usually if we say "agree upon" a policy, two or more people will discuss it, then decide on the best policy. It is an event, not a statement of being for the new policy. "The group met and after some discussion, agreed upon the new policy." "I disagree with the new policy" is correct You would never say "I disagree upon the policy." He is going to visit the USA in July. [This is a period of time, without a particular day - it means sometime within the month of July] He is going to visit the USA on July 2, 2012. [This is a definite day, so it is "on"]

I agree with the new policy or if more than one policy it would be 'I agree with the new policies' I disagree with the new policy or I disagree with the new policies. I am waiting for you since morning. He is going to the USA in July. You don't need to say 'visit' He is going to the USA in July 2012 or if it was a specific date you would say 'He is going to the USA on the 4th of July 2012'. Hope this helps you!

I agree with the new policy I am waiting for you since the morning in July :)