Tourists should keep in mind that they are representing their motherland while abroad, so they need be _______ about their behaviour.

My friend Martin was very sick with a strange fever; _____, he could neither eat nor sleep[ ]

We have known the boy very well _______came to our school last term..

By talking with them，I get to know ________ Russian people see their country and the US.

Beijing is one of the in the world today.