光纤传输可以得到高质量的图像和远距离的传输，可把传输环节看做视频输入或视频输出的黑盒子。（）
参考答案：对
The programs of UNICEF have saved thousands of African children who would have died from hunger or disease.
A．instead
B．therefore
C．otherwise
D．moreover
计算题：水处理需用5米310％的食盐水浸泡树脂，求需用纯度为98％的食盐多少千克？
