Irregular verbs 不规则动词变化表 understand understood understood win won won bring brought brought buy bought bought think thought thought fight fought fought catch caught caught teach taught taught A B C 8 u begin began begun drink drank drunk ring rang rung sing sang sung sink sank sunk swim swam swum 4Irregular verbs 不规则动词变化表 4 understand understood understood win won won bring brought brought buy bought bought think thought thought fight fought fought catch caught caught teach taught taught A i B a C u begin began begun drink drank drunk ring rang rung sing sang sung sink sank sunk swim swam swum