Exercise 9. Underline the mistake:

1.       When waiting to buy tickets, you shouldn't queue in a row.       

2.       There is a custom that Vietnamese teachers should to wear Ao dai at school.

3.       When coming to America, you shouldn't tip the waiter 10% of the bill.

4.       You must to use the right hand when eating in India.

5.       You mustn't drive on the left in Britain.

6.       Young people have bow your head to greet adults in some Asian countries.

7.       In the past, Vietnamese women hadn't to stay at home doing housework.

8.       As a worker, he have to wear protective clothes.