A:NaF
B:NH4Cl
C:HClO
D:HNO3
In America, you can open your presents immediately. You don't have to ______!
描出所有的长方形。
—________. It's in the box.
有一种新型锁﹣﹣声纹锁.只要主人说出事先设定的暗语就能把锁打开,别人即使说出暗语也打不开.这种声纹锁辨别声音的主要依据是( )