北回归线自东向西穿过的我国四个省(区)是( )
Kate isn't happy because she lost her pet. Let's go to cheer her up.
一定质量的化合物与4.8 g氧气恰好完全反应, 只生成4.4 g二氧化碳和2.7g水。下列对该化合物元素组成的判断中,正确的是()