【单选题】If something seldom happens, it:
【单选题】营养不良患儿用药,下列哪项药物具有提高味觉敏感度、增加食欲的作用:
【单选题】If anything _____ the computer, please let me know. [ ]
【单选题】______________ the day before yesterday. [ ]
A.
something happens to him
B.
He happens to something
C.
Something happened to him
【多选题】下列叙述正确的是( )
A.
浓度均为0.1mol?L -1 的小苏打溶液与烧碱溶液等体积混合:c(Na + )+c(H + )=2c(CO 3 2- )+c(OH - )+c(HCO 3 - )
B.
某二元酸(用H 2 A表示)在水中的电离方程式是:H 2 A=H + +HA - ,HA - ≒H + +A 2- 则NaHA溶液中:c(Na + )=c(A 2- )+c(HA - )+c(H 2 A)
C.
pH=12的氨水与pH=2的盐酸等体积混合:c(Cl - )>c(NH 4 + )>c(H + )>c(OH - )
D.
常温下,10 mL pH=12的Ba(OH) 2 溶液与40 mLcmol?L -1 的NaHSO 4 溶液混合,当溶液中的Ba 2+ 、SO 4 2- 均恰好完全沉淀,若混合后溶液的体积为50 mL,则溶液pH=11
【单选题】'It happens that he was in business. ' The sentence means that______.
A.
He happens to be on business
B.
He happened to be on business
C.
He happens to have been on business
D.
He happened to being on business
【简答题】已知水在25℃和95℃时,其电离平衡曲线如图所示: (1)则25℃时水的电离平衡曲线应为______;(填“A”或“B”),请说明理由______; (2)25℃时,将pH=9的NaOH溶液与pH=4的H 2 SO 4 溶液混合,若所得混合溶液的pH=7,则NaOH溶液与H 2 SO 4 溶液的体积比为______;曲线B对应温度下,250mL 0.lmol/L的HCl溶液和250mL0.3mol...