题目

分子式为C5H11Cl的同分异构体共有（不考虑立体异构）（   ） A．6种            B．7种       C．8种            D．9种 答案：C 观察下列句子，试着归纳其画线部分所包含的句型结构。 1．And they are easy to learn． __________________ 2．Have some low-risk conversation openers ready． __________________ 3．It is estimated that 80％ of all conversation in English is small talk． __________________