bounce的过去式和过去分词分别是bounced。在英语中，动词的变化规律通常遵循以下规则：

1. 规则变化：对于大多数动词，过去式和过去分词的形式相同，或者只需要在动词原形后加上-ed。例如：

– walk → walked → walked

– run → ran → run

– jump → jumped → jumped

2. 不规则变化：有些动词的过去式和过去分词形式与原形不同，这些动词的变化通常没有固定的规律，需要单独记忆。例如：

– go → went → gone

– have → had → had

– do → did → done

– see → saw → seen

– be → was/were → been

– come → came → come

– go → went → gone

– put → put → put

– take → took → taken

– drink → drank → drunk

– eat → ate → eaten

– break → broke → broken

– drive → drove → driven

– find → found → found

– give → gave → given

– know → knew → known

– leave → left → left

– make → made → made

– play → played → played

– read → read → read

– say → said → said

– see → saw → seen

– show → showed → shown

– sing → sang → sung

– sleep → slept → slept

– speak → spoke → spoken

– spend → spent → spent

– take → took → taken

– teach → taught → taught

– write → wrote → written

3. 规则动词的过去式和过去分词：对于规则动词，过去式和过去分词的形成通常遵循以下规则：

– 一般规则：在动词原形后加上-ed。例如：play → played

– 以辅音字母结尾的动词：如果动词以辅音字母结尾，且该辅音字母不是重音，则通常在-ed前加上一个元音字母。例如：stop → stopped

– 以重读闭音节结尾的动词：如果动词以重读闭音节结尾，且该闭音节的重音在最后一个辅音上，则在-ed前加上一个元音字母。例如：dance → danced

– 以元音字母结尾的动词：如果动词以元音字母结尾，则直接在后面加上-ed。例如：live → lived

在“bounce”这个动词中，由于它属于不规则动词，其过去式和过去分词形式都是“bounced”。这类动词的变化没有简单的规则可循，因此需要单独记忆。