在△ABC中AR→=2RB→,P是CR中点.若AP→=mAB→+nAC→,则m+n等于( )
下列词语中划线字注音全部正确的一项是 ( )
When Lily worked as a nurse in the hospital, she experienced a joy in helping people ________ trouble.
如图是三大类岩石关系示意图,图中序号①一⑥分别代表岩浆、喷出岩、侵入岩、沉积物、沉积岩、变质岩中的某一项,图中代表沉积岩和变质岩的是( )