Hi Hamid, First of all, you should know that a 'Trip' is the process of travelling from one place to another, staying there, usually for a short time, and coming back again. So , you should say, for example: ''I went on a trip the other day!'' ***NOTICE: You 'take' or 'go on' a trip. (e.g.: ''We took a bus trip to Manchester.'') 1) Where did you go on a trip? = You had best say: ''Where did you go on a trip to?'' 2) Who did you go on a trip with? = that is correct! 3) I was on a trip (or I was on the trip) = I should think that you could say: ''I was on a trip'', although I have always heard people saying ''went on a trip'' or ''took a trip'' 4) I took a trip to Paris = that is OK! Hope that helps!

Thanks a lot.

Yes.