例句與造句

1. ranging from 100 to 200 microns across, the width of several human hairs, these microscopic fossils are surprisingly complex and constitute almost a textbook example of a bilaterian, including the three major tissue layers ( the endoderm, mesoderm and ectoderm familiar from high school biology texts ), the presence of a gut with a mouth and anus, and paired coeloms ( body cavities ) surrounding the gut
   這些微化石的大小為100~200微米，相當(dāng)于幾根頭發(fā)的寬度，?們看起來出奇復(fù)雜，而且簡直就像兩側(cè)對稱動(dòng)物的教科書般，展示了各種特徵：包括三個(gè)主要的組織層（內(nèi)胚層、中胚層及外胚層，都是中學(xué)生物課本中熟悉的名詞），前后連接口部與肛門的腸腔，腸腔外還圍繞著成對的體腔。
2. It's difficult to find ectoderms in a sentence. 用ectoderms造句挺難的