A:Na2SO4溶液加入BaCl2固体
B:Ba(OH)2溶液中加入CuSO4(少量)固体
C:NaOH溶液通入HCl
D:H2O中加入NaCl固体
The students stopped ____ (talk) when the teacher came in.
自信对于任何一个人都是至关重要的。下列体现自信态度的是 ( )
如图,A、D是⊙O上的两个点,BC是直径,若∠D = 35°,则∠OAC的度数是( )