1. 内胎   gear lever   inner tube   wheel   tire   Hint Half-n-half Clue   2. 轮胎   horn   motorcycle   tire   handbrake   Half-n-half Clue   3. 引擎   tire   engine   handbrake   exhaust pipe   Half-n-half Clue   4. 三轮车   spoke   tire pressure   pump   tricycle   Half-n-half Clue   5. 轮幅   inner tube   spoke   seat   handbrake   Half-n-half Clue   6. 扣练齿轮   engine   horn   sprocket   inner tube   Half-n-half Clue   7. 锁   exhaust pipe   lock   sprocket   wheel   Half-n-half Clue