Употребите Past perfect :
a)Just before he had the accident, the motorcyclist (overtake) an estate car. b) When Mrs Turner looked for her cameras in the back of her car, she could not find them. They (be) stolen while she was helping the motorcyclist. She (be) in such a hurry to reach the injured young man that she (leave) the back of the car open. The thief (take) the bag with the equipment while everybody was concentrating on the accident. c) I got "bumped" because I (check) in later than everybody else. d) When she (check) in, she went to the duty-free to buy some whisky and cigarettes. e) When she arrived at her destination, she had to pay duty on the things she (buy) at the duty-free on her departure. f) Several passengers were injured because they (not fasten) their seat belts.

Just before he had the accident, the motorcyclist had overtaked an estate car. b) When Mrs Turner looked for her cameras in the back of her car, she could not find them. They had been stolen while she was helping the motorcyclist. She had been in such a hurry to reach the injured young man that she had left the back of the car open. The thief had taken the bag with the equipment while everybody was concentrating on the accident. c) I got "bumped" because I had checked in later than everybody else. d) When she had checked in, she went to the duty-free to buy some whisky and cigarettes. e) When she arrived at her destination, she had to pay duty on the things she had bought at the duty-free on her departure. f) Several passengers were injured because they had not fastened their seat belts.