Please answer the following question: Before you go to another country, it is a great help if you know the language and some of the customs of the country. When people meet each other for the first time in Britain, they say "How do you do?" and shake hands . Usually they do not shake hands when they just meet or say goodbye. But they shake hands after they haven't met for a long time or when they will be away from each other for a long time. Last year a group of German students went to England for a holiday. Their teacher told them that the English people hardly shake hands. So when they met their English friends at the station, they kept their hands behind their backs. The English students had learned that Germans shake hands as often as possible, so they put their hands in front and got ready to shake hands with them. It made both of them laugh. It is _ if you know the language and some of the customs of the country. A) not useful B) not helpful C) very helpful D) very bad
A:
C