【单选题】赶年起源于( )嘉靖年间,土家子弟因奉命抗倭而提前过年团圆,以送子弟出征。
【多选题】在△ABC中,| AB |=3,| AC |=4,| BC |=5,则 AB ? BC + BC ? CA + CA ? AB 的值是( )
【简答题】7 It is polite to call someone fat and ugly.
____
【单选题】_My parents always tell me_______others late at night. _They are right. It’s not polite.
【简答题】It is not polite to ask____ questions.
【单选题】[天津 理综2016·2,6分]下列对氨基酸和蛋白质的描述正确的是
C.
α-氨基丙酸与α-氨基苯丙酸混合物脱水成肽,只生成2种二肽
D.
氨基酸溶于水过量氢氧化钠溶液中生成离子,在电场作用下向负极移动