John is bringing his son _______ him[ ]
In ancient times, dogs were mainly ______helping people hunt( 打猎) .Now they are more useful-they can help the blinds, search for the bad eggs.
Knowing how to _______ a map can help you when you are travelling in a strange place.
Some people said _____ that Copenhagen Conference
Did you read a book about customs last week?– Yes, I found ______ very useful to know the customs of foreign countries.