Here are the completed sentences for your questions:

**Question 33:** Helen started to learn Chinese in 2000.
=> Helen has been learning Chinese since 2000.

**Question 34:** About thirty million people are watching this programme.
=> This programme is being watched by about thirty million people.

**Question 35:** The boys said, “We have to try our best to win the match.”
=> The boys said that they had to try their best to win the match.

**Question 36:** She asked Lan how many members there were in her family.
=> She asked Lan: “How many members are there in your family?”