A:HCl、NaOH、NaCl
B:KNO3、NaCl、FeCl3
C:NaOH、Na 2CO3、NaCl
D:CuSO4、H2SO4、NaCl
在图1中画出光线经过凸透镜后的光路图(O为光心,F为焦点);在图2中,根据通电螺线管的N、S极,分别标出电源的正负极和两个小磁针静止时的N、S极.
On June 1st, 2015, the “Oriental Star(东方之星号)” turned upside down. People all over the world ______.