Hi Bonnie, I guess it's such a huuuuuuuuuge topic that can be discussed all day long:) In a nutshell, it's not that difficult, just take it easy and see some examples below: "He sent me the present which he bought in the US" ("He sent me the present he buying in the US"), "He sent me the present which was bought in the US" ("He sent me the present bought in the US")

Since nobody else took a stab at this I will. If you research attributive clause on the internet it appears there is some disagreement about the exact definition or if it really should be called a relative clause. But simply it seems to mean a clause (section of a sentence) that modifies the noun before it. "She was a excellent teacher who was always willing to help her students" "who was always willing to help her students" is the attributive clause that modifies the earlier noun "teacher" This is the best I can come up with.