单项选择题
He asked me how often I went back home ____ a visit whe...
单项选择题He asked me how often I went back home ____ a visit when I was at college.（ ）
Do you want to change this lamp for ____ or do you want...
单项选择题Do you want to change this lamp for ____ or do you want your money back?（ ）
He left for New York ____ I could say goodbye to him.（ ...
单项选择题He left for New York ____ I could say goodbye to him.（ ）
