右图是鸟卵的结构示意图,图中表示胚盘的结构部位是
A:①
B:②
C:③
D:④
某种商品如果以240元售出,则可以获得20%的利润,则该商品的实际进价为 ____ 元.
—China's first large passenger plane C919 flew successfully on May 5.
—Yes. What's more, it was built on our own in Shanghai.
已知双曲线过点4,3且渐近线方程为y=±12x,则该双曲线的标准方程是____
He is writing _________ his parents.