He followed her up a rickety staircase to a squalid bedsit.他跟着她上了一段摇摇晃晃的楼梯，来到了一间邋遢的卧室起居室两用房间。Mona climbed the rickety wooden stairway.莫娜爬上了摇摇晃晃的木楼梯。He was precautious in crossing the rickety bridge.走过这座摇摇晃晃的桥时他小心翼翼....
He was precautious in crossing the rickety bridge.走过这座摇摇晃晃的桥时他小心翼翼.He followed her up a rickety staircase to a squalid bedsit.他跟着她上了一段摇摇晃晃的楼梯，来到了一间邋遢的卧室起居室两用房间。He followed her up a rickety staircase to a squalid bedsit.....
重复的 、 残留的及低等的构造易于变异.Multiple, rudimentary, and lowly organized structures are variable.微孢子虫作为一类专营细胞内寄生的低等的原生动物, 有着比较悠久的进化历史.Microsporidia are parasitic protozoa, and have a relative long evolution history.许多地位低等的凡人视其为惺惺作...