A:see
B:look
C:watch
图中甲是在有光照条件下验证氧气是否由绿色植物释放出来的装置;乙和丙是另2个装置,通常可作为甲的对照实验的装置是( )
如图,在四边形ABCD中,若∠1=∠2,则AD∥BC,理由是( )
— About 379 people died the earthquake in Ludian, Yunnan Province.
— What bad news!