A是分子式为C7H8的芳香烃,已知它存在以下一系列转化关系,其中C是一种一元醇,D是A的对位一取代物,H与E、I与F分别互为同分异构体:
下列有关北京的叙述,正确的是( )
如图所示,一质量为m的物体沿倾角为θ的斜面匀速下滑.下列说法正确的是( )
Larry, we're glad you have arrived. We ______ to drive to the station to meet you.