during the test we were supposed to stay in our seats,keep our eyes on ourwork,___to anyone.

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• during the test we were supposed to stay in our seats,keep our eyes on ourwork,___to anyone.A and not speak B instead of speaking
• During the test we were supposed to stay in our seats,keep our eyes on our work,_____to anyone.A.and not speak B.rather than speak C.instead of speaking 答案选择A这个我理解 但B和C怎么不能选呢?我们被要求坐在座位上,做自己的功课,而不是和别人说话.语法方面有什么不妥么?
• during the test we were supposed to stay in our seats,keep our eyes on ourwork,___to anyone.
• During the test we were supposed to stay in our seats,keep our eyes on our work,_____to anyone.
• 某二元酸H2A溶液按下式发生一级和二级电离;H2A==H++HA- HA-==H+A2- 已知相同浓度时的电离程度a(H2A)＞某二元酸H2A溶液按下式发生一级和二级电离;H2A==H++HA- HA-==H+A2-已知相同浓度时的电离程度a(H2A)＞a(HA-),设有下列四种溶液；A 0.01mol/L的H2A溶液B 0.01mol/L的NaHA溶液C 0.02mol/L的HCl溶液与0.04mol/L的NaHA溶液等体积混合D 0.02mol/L的NaOH溶液与0.02mol/L的NaHA溶液等体积混合(1)其中H2A浓度最大的是______,最小的是_______.(2)其中H+浓度最大的是_______,最小的是_______.(3)其中A2-浓度最大的是_________,最小的是______.
• 某二元酸（H2A）在水中的电离方程式为H2A===H+ + HA- ,HA- ⇌ H+ + A2-某二元酸（H2A）在水中的电离方程式为H2A===H+ + HA- ,HA- ⇌ H+ + A2-（25℃时Ka+1.0x10^-2）,下列有关说法正确的是（）A.H2A是弱酸B.稀释0.1mol/LH2A溶液,因电离平衡向右移动而导致c(H+)增大C.在0.1mol/L的H2A溶液中,c(H+)=0.12mol/LD.若0.1mol/LNaHA溶液中c(H+)=0.02mol/L,则0.1mol/L的H2A中c(H+)