已知戊醇(C₅H₁₂O)共有8种属于醇的同分异构体，请回答：
(1)戊醇的这8种同分异构体中能氧化成醛的有4种，它们是：CH₃(CH₂)₃CH₂OH和(写结构简式)____________________________________________________________________
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(2)戊醇的这8种同分异构体脱水后可得________种烯烃．