在横线上填入合适的介词。 1. It is wise of him to combine business ________ pleasure. 2. She serves _________ a tour guide in high season. 3. The shopkeeper wanted to charge me 20 yuan ________ parking my car in front of his shop. 4. The thief was sentenced ________ two years in prison. 5. The lawyer accused the couple ________ abusing their children. 6. The lawyer charged the couple ________ abusing their children. 7. Factories offer their workers masks free ________ charge. 8. He was arrested _________ stealing a necklace.