Sure! Here are the sentences filled in based on the prompts:

1. It was several months since Jessica last went on a train.
Jessica hadn't been on a train **for** several months.

2. Jessica bought her ticket in advance online.
Jessica's ticket **was** bought in advance online.

3. It wasn’t easy to find a seat because the train was crowded.
The train was **so** crowded that it was difficult to find a seat.

4. Jessica asked what time they would arrive in York.
Jessica asked ‘What time **will** we arrive in York?’

5. The journey wasn’t boring for Jessica because she had a good book.
Jessica **did not** find the journey boring because she had a good book.