A:0.01 mol/L的H2A溶液
B:0.01 mol/L的NaHA溶液
C:0.02 mo|/L的NaOH溶液与0.02 mol/L的NaHA溶液等体积混合
D:0.02 mol/L的HCl溶液与0.04 mol/L的NaHA溶液等体积混合
不等式x﹣4<0的解集是____ .
-Jeff seems unhappy. What's the matter?
-He got his bike lost this afternoon. Let's go to __________ him __________.
在太阳系中,太阳是( )