Combine two sentences into a new one using the given words in brackets.
1. He smokes too much. That why he can't get rid of his cough. (could)
2. The car was very expensive. He couldn't afford it. (rich)
3. I whispered as i didn't want anybody to hear our conversation. (so that)
p/s: Câu nào có công thức riêng chỉ mình luôn với