1.Because about fifty million people have to go to the doctor because of it.
(câu 2 dòng 1)
2. No,they can
(Đầu dòng thứ 3)
3. Yes,they may
(They may also..head)
4..People have headaches when they work too hard or they are too nervous about something.
(Cuối dòng thứ 4 từ dưới lên)