1.YesterdayMr.Zhanghadabarbercuthishair.

　　->YesterdayMr.Zhanghadhishaircut.

　　cut过去分词cut,havesth.done将什么事做了

　　2.Thebridgewhichwasbuiltinthepastisstillingoodcondition.

　　->Thebridgebuiltinthepastisstillingoodcondition.

　　将从句主谓去掉即可,build过去分词built表示被动的意思

　　3.Thoughhewaslaughedatbymanypeople,hecontinuedhisstudy.

　　->Thoughlaughedatbymanypeople,hecontinuedhisstudy.

　　同上改法,laugh过去分词laughed表示被动的意思

　　4.Wedon'twanthumancloningthatareproducedbyscientiststoreplaceusoneday.

　　->Wedon'twanthumancloningproducedbyscientiststoreplaceusoneday.

　　同上改法,produce过去分词produced表示被动的意思

　　5.Manypeoplebelievethattheproblemsthatarecreatedbycloningwillsoonbeclear.

　　->Manypeoplebelievethattheproblemscreatedbycloningwillsoonbeclear.

　　同上改法,creat过去分词created表示被动的意思