bring buy think 过去式,变化规律： begin drink ring sing swim sit 过去式

ing [briŋ]
v. 带来
[ 过去式brought 过去分词brought 现在分词bringing 第三人称单数brings 名词bringer
buy [bai]
n. 购买,买卖
v. 买
[ 过去式bought 过去分词bought 现在分词buying 第三人称单数buys 形容词buyable ]
think [θiŋk]
v. 想,考虑,想像
[ 过去式thought 过去分词thought 现在分词thinking 第三人称单数thinks ]
没有固定的规律可循

brought bought thought
began drank rang sang swam sat

brought bought thought
began drank rang sang swam sat
看出来了没

brought bought thought
这三个共同点是，过去式都是有ought；同时要注意：teach--taught