题目

Today, a quarter of the world's population uses English, and as _________ as one billion people are learning it. A . much B . many C . more D . most 答案：B19．下列计算正确的是（　　）A．$\root{3}{8}=±2$B．-$\root{3}{-7}=-\root{3}{7}$C．$-\sqrt{\frac{16}{9}}=-\frac{4}{3}$D．$\sqrt{\frac{9}{4}}=±\frac{3}{2}$