Combine the following sentences using the given words in the brackets.
1. He drove very fast. He had an accident. (Because of)
2. This problem is very difficult, We can't solve it now. (so)
3. The girl is very beautiful. Her dress is red. (whose)
4. She learns English well. She plays sports well, too. (not only...but also)
5. She is intelligent. She can do this exercise by herself. (enough)