В каждом предложении есть только 1 ошибка. Помогите найти её

1. The children are looking к the picture
2.She said she will help me to cook the pizza
3.He asked me how long I was learning English
4. They played in the garden when it began to pour
5.Nobody know the answer to this question
6.A book that you gave me is very interesting
7. All the citizens must to know this law
8. The supermarket had built last year