第1个回答 2011-01-28
This is the dictionary I bought last week.
第2个回答 2011-01-28
It is the dictionary that I bought yesterday. 要用强调句
第3个回答 2011-01-28
it was the dictionary that I bought yesterday.注意从句是过去时。主句用was
第4个回答 2011-01-28
It is the dictionary that I bought last week.