吡啶分子中氮原子上的未共用电子对不参与π体系,这对电子可与质子结合。为什么吡啶的碱性比脂肪族胺小得多?
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[音频]...so that the trustees ______ what to do with the money. (来源于网络)
A. concern that
B. have no idea
[音频]I'm being ignored. Come ______. (来源:美剧《广告狂人》)
A. spend time with me
B. bring me the time
[音频]...it really does _____ those cultural and immigration anxieties... (来源:CNN新闻)
A. result from
B. be different from
[音频]...because the lion's literally _____. (来源:纪录片《侏罗纪搏击俱乐部》)
A. having to insist
B. having no other choice