例句與造句

1. Feather growth begins with a thickening of the epidermis called the placode , which elongates into a tube ? the feather germ [ see illustration above ]
   首先，表皮上的基板開始增厚，并拉長(zhǎng)成一根管子，稱為羽芽（見(jiàn)上方羽毛的成長(zhǎng)過(guò)程） 。
2. It's difficult to find placode in a sentence. 用placode造句挺難的