精度很高．表面粗糙度值很小的表面，要安排光整加工，提高加工表面尺寸精度和表面质量．
参考答案：对
The people in Ya'an have met lots of difficulties, but they haven't ________ hope.
A．picked up
B．given up
C．looked for
D．waited for
A．变小
B．变大
C．保持不变
D．无法判断
