Mr. Green ______ goes shopping, because he is ______ busy working.
This is the primary school ________ I studied three years ago.
Please pass me the cartoon book ________ has a Mickey Mouse on the cover.
I hate people _______ talk much but do little.
---Where is the scientist ________ gave us the talk yesterday?---He has gone back to Qinghua University.
The letter _______ I received from him yesterday is very important.