问题
选择题
—_____ do I save the document?
—You click "save" again.[ ]
A. What
B. How
C. Where
D. When
答案
答案：B
搜题请搜索小程序“爱下问搜题”
—_____ do I save the document?
—You click "save" again.[ ]
A. What
B. How
C. Where
D. When
答案：B
+2H+=H2O+SO4↑
=BaSO4↓+NH3↑+2H2O
+ OH－
H2S+2OH－
的少量Ca(HCO3)2溶液：Ca2++HCO