No one taught French. He learned it all by .
A:himself; him
B:he; himself
C:him; himself
明代中叶以后,土地押租制流行。而佃农的佃权,即土地经营权,是有偿取得,遂可以有偿转佃和出典。这反映了( )
如图为胡萝卜素粗品鉴定装置和鉴定结果示意图,请据图回答下列问题:
①图中所用的胡萝卜素粗品鉴定的方法名称是____ .
②a的作用是____ .
③A、B、C、D四点中,属于标样的样点是____ .
④乙代表的物质是____.
161×6=____