The city government impounded his motorcycle because the owner had unpaid tickets.

### 解释 impounded 是动词 impound 的过去式，impound 由前缀 im-（表示"进入"）和 pound（"围栏、畜栏"）组成，原指"将牲畜关入围栏"，引申为"依法扣押财物"的意思。