(Past simple or Past Continuous).
example:
1. By the time the train left (leave), it was getting (get) dark
A. left / got B. leave / get C. left / was gettingX

2. I (still/look) for my seat when the train (stop) for the first time.
A. still looked / was stopping B. still was looking / stop C. was still looking / stopped

3. I (meet) a family from Venezuela, who (go) to a wedding in Paris.
A. was meeting / were going B. were meeting / were going C. met / went

4. When I (wake up) in the morning, the train (travel) through the vineyards.
A. were waking up / were travelling B. woke up / travelled C. woke up / was travelling

5. The train (be) late and my friends (not/wait) for me so I (take) a taxi to their house.
A. was / were not waiting / took B. were / was waiting / was taking C. was / waited / taked