The old couple often take a walk after supper in the park with their pet dog them. [ ]

Are your teachersbig and strong —______.

In my opinion , Tianjin is not as expensive in price as Beijing but Tianjin is in traffic.

The math problem is too difficult for us to _______.

Can you tell me why you learn English so well—It’s very simple. ____you work, ____ grades you will get.