用括号里单词的适当形式填空
1. When I am ________ (do) my homework, my mother is ________ (cook).
2. He has to _________ (travel) the country in search of work.
3. How __________ (do) seeds travel?
Seeds _________ (travel) in many ways.
4. What _____ (be) they talking about?
They are _________ (talk) about the seeds of plants.