Как понять в каком вопросе ставится is, are?

В зависимости от подлежащего,если оно стоит в единственном числе -ставится is,если во множественном -are.Обратите внимание,что это относится только к настоящему времени.
К тому же не стоит забывать о местоимениях-He,she,it is;We,they,you are.

Is используется для существительных 3 лица: He, She, It
Are для 2 лица: You, we, they

1) A large boat that is used for travelling by sea. Ship, liner
2) The English for " экзотический" exotic
3) You need this document if you travel abroad. passport
4) This book gives you information about a country you are going to visit. guide-book
5) The opposite of "boring". interesting
6) American slang for "hello". hi
7) A person who travels. traveller
8) What you need to get into a train or a plane. ticket
9) A long journey by sea. cruise
10) Madame Tussaud's is a museum in London.
11) It helps you not to get lost. map
12) You must be careful of this person in some cities. robbers
13) When in Rome, do as the __ Romans __ do.
14) A place where tourists usualy stay when travelling. hotel
15) Let's meet _at_ the railway station.
16) This language is understood in nearly every corner of the world. English
17) How _long_does it take to get from Europe to NEW-york?
18) Tourists spend most of their time seeing the _ sights __.
19) You need it if you want to take pictures. camera
20) The English for "туризм". tourism
21) The language spoken in Turkey. Turkish

The name of E.C is well known all over the world. He sang in many countries. People like his singing.Though Caruso was very famous he often said: "No man is so well known as he thinks he is."One day, when he came to the United States his car broke down and Caruso asked the farmer to do it. The farmer agreed. While the farmer was repairing the car, Caruso entered the farmer's house to rest there. Caruso paid the farmer for his work and presented him his photograph with his name on it. The farmer read the name on the photograph and cried out:"Oh, what a luck! You are Robinson Cruso! I've never dreamed to receive the greatest traveller in the world in my poor house!"