Sure! Here are the rewritten sentences:

1. We were all surprised when she suddenly came back.
We were all taken by surprise by her sudden return.

2. She usually drinks a glass of milk before going to bed every night.
She is in the habit of drinking a glass of milk before going to bed every night.

3. I find it impossible not to worry about Tom.
I can’t help but worry about Tom.

4. I arrived late, the traffic was so bad.
I am sorry, but if the traffic hadn’t been so bad, I would have arrived on time.

5. I arrived late, the traffic was so bad.
I am sorry, but if it weren’t for the bad traffic, I wouldn’t have arrived late.

6. You must not smoke in here.
Smoking is not allowed here.

7. She left because he was so unpleasant.
It was his unpleasantness that made her leave.

8. We’ll stop now unless you have any further questions.
Provided you don’t have any further questions, we’ll stop now.