在改写后的句子中填入所缺单词，使其与原句意思相符。
1. His cousin could swim when she was four years old.
His cousin _______ _______ _______ swim when she was four years old.
2. My father didn't watch TV last night, but he read some newspapers.
My father _______ some newspapers _______ _______ _______ TV last night.
3. I don't think he can work out this problem alone.
I don't think he can work out this problem _______ _______.
4. At last the boy opened the box with a knife.
_______ the boy _______ a knife _______ _______the box.
5. Suzy does well in Maths.
Suzy _______ _______ _______ in Maths.