【简答题】如图是同一个胚胎在不同发育时间的照片,请你仔细观察并分析回答: (1)胚胎的发育是由______开始的,经过细胞的不断______,逐渐发育成胚胎. (2)胚胎发育的部位是在母体的______内.比较照片A和B的胚胎,哪个发育的时间长些?你判断理由是______. (3)照片A中,胚胎腹部有“索状”的结构,这个结构是______.它与母体通过______相连,这样能够使胚胎与母体之间进行物质交换....
【单选题】Choose between the present simple and present continuous. She ________ this event every month.
【单选题】Why isn't Wendel running at this year's event?
A.
She has a golf engagement.
D.
She has a running injury.
【单选题】She ———— this event every month.
【单选题】She __________ this event every month.
【单选题】犁式 C形转弯是由( )开始,逐渐进入转弯。
【单选题】She _______ this event every month.