选出每组中不同类的一项。
①A. photo B.picture C. climb ____
②A ride B. holiday C. stay ____
动、植物成体的体细胞进行离体培养中,下列叙述正确的是( )
His parents didn't earn much money so he dropped out of school because of p____(贫穷).
下列各句与例句句式特点相同的一项是( )
例:固一世之雄也,而今安在哉?
如图为肺的内部结构示意图,图中所示肺泡外包围着毛血管,肺泡壁和毛细血管都很薄,由一层上皮细胞构成,这有利于( )