Exercise 3. Use a relative pronoun preceded by a preposition to combine each pair of the sentences below (Sử dụng đại từ quan hệ với một giới từ đứng trước nối các câu dưới đây) 1. The boy is my son. You made fun of him. 2. This lesson is of paramount importance. You should pay great attention to it. 3. The old woman is my grandmother. You gave place to her on the train. 4. This snake is not poisonous. You should not be afraid of it. 5. The English contest lasted for more than four hours. I was successful in this contest. 6. These children are homeless. The old woman takes care of them. 7. The two boys are naughty. You are acquainted with them. 8. This is the result of our work. I am happy with it. 9. This is a one-way street. I don’t take notice of it. 10. She is a new secretary. I am responsible for her at work.