Hi, could you please tell mi which of the following sentences are correct? Are there any differences in meaning?<br/><br/>Yesterday I met an old friend who I went to school with.<br/><br/>Yesterday I met an old friend who I was going to school with.<br/><br/>Yesterday I met an old friend who I had gone to school with.<br/><br/>Yesterday I met an old friend who I had been going to school with.