Our English teacher advises us ____________ more after class.

The children,____ had played the whole day long, were worn out.

My uncle worked as a volunteer in Tibet last year. He told me a lot of his unforgettable _________ while working there.

He kept on _______ the mountains all by _______ for three days.

These animals are all used to their environment,______, they have learned how to live successfully in their habitat．