吸附在皮肤、呼吸道、消化道黏膜上的抗体
已知碳碳单键可以绕键轴旋转,某烃的结构简式如图,下列说法中正确的是
My grandfather would be fine for a while, but would then fall suddenly ill and have to________the hospital.
魏源和严复最大的共同点是( )