Вопрос по английскому языку:

Look back at the text again. Find
sentences with that / which / who. What do
these words mean? Complete the following
sentences:
1. The pamphlet was written by Voltaire (that/
which/who) was a famous...
2. Voltaire wrote a letter (that/which/who)
only contained...
3. The publisher sent an answer (that/which/
who)...
4. All copies of the pamphlet (that/which/who)
was written by Voltaire were...
Помогите умоляю
Срочно!!!!!!