①____ Na2S2O3+____HCl→____ NaCl+____S+____SO2↑+
____H2O
②____ Zn+____H++____NO3﹣→____ Zn2++____NH4++____H2O.
如图,已知AB是半圆O的直径,∠BAC=32°,D是弧AC的中点,求∠DAC的度数.