①O2和O3 ②35Cl和37Cl ③CH3CH3和CH3CH2CH3 ④氯仿和三氯甲烷
⑤CH3CH2CH(CH3)CH2CH3和CH3CH2CH(CH3)CH(CH3)CH3
⑥
⑦CH3(CH2)2CH3和(CH3)2CHCH3 ⑧CH3CH(CH3)CH3和CH(CH3)3