My mom always _______ she's busy.
A:says
B:speaks
C:tells
D:talks
有关纬线和纬度的说法,正确的是( )
图甲:玻璃珠被加热后,小灯泡发光.说明____;
图乙:半导体二极管D接入电路,小灯泡发光,调换电池的正负极后,小灯泡不发光.这说明____.