Разберем каждое предложение и найдем ошибку.
- How many does it cost? → How much does it cost?
- The T-shirt isn't enough big. → The T-shirt isn't big enough.
- Americans are speaking English with an American accent. → Americans speak English with an American accent.
- He went to New York ago two years. → He went to New York two years ago.
- While he was visiting Hollywood, he was meeting a famous actor. → While he was visiting Hollywood, he met a famous actor.
- I meet hardly ever Americans in my city. → I hardly ever meet Americans in my city.
- The smaller US state is Hawaii. → The smallest US state is Hawaii.
- J.F. Kennedy were a president. → J.F. Kennedy was a president.
- Mark Twain was a famous American novel. → Mark Twain was a famous American novelist.
- Travelling by plane is more expense than travelling by train. → Travelling by plane is more expensive than travelling by train.
Ответ: смотри решение выше.