Do you remember those days ________ we spent along the seashore very happily?[ ]

A.when  

B. where  

C. which  

D.on which

某烯烃3.5g跟溴水充分反应，得到的无色液体质量为11.5g，则该烃的化学式为 [ ]

A.C₂H₄    

B.C₃H₆    

C.C₄H₈   

D.C₅H₁₀