题目

In 2015, a bill allowing every couple to have two children was _____ in China. A. appointed              B. approved                C. adjusted                D. abandoned 答案：B下图是一个横断面为抛物线形状的拱桥,当水面宽4 m时,拱顶(拱桥洞的最高点)离水面2 m,当水面下降1 m时,水面的宽度为_____m.