如图,直线a∥b,直线l与a相交于点P,与直线b相交于点Q,且PM垂直于l,若∠1=58°,则∠2= ____.
关于对摩擦力的认识,下列说法正确的是 ( )
如图所示,在“探究平面镜成像特点”实验中:
Shanghai lies _______ the east of China and _______ the northeast of Guangdong.
①KOH Na2SO4 AlCl3 ②NaHCO3 NaNO3 H2SO4
③HCl NaAlO2 NaCl ④Ca(OH)2 Na2CO3 BaCl2.