1. They walked together as far as the second crossing ____ they parted .
A. when B. which C. why D. where
2. Martin Cooper , a US researcher , was considered _______ the first cell phone .
A. invented B. to invent C. having invented D. to have invented
3. I don’t think that rock music is terrible , ______?
A. do I B. don’t I C. is it D. isn’t it
