简述造成折弯尺寸出现偏差的主要原因。
参考答案：
主要有定位是否准确，材料的放置是否偏斜，折弯上、下模工作线（面）是否平行。
A dozen ideas were considered____the chief architect decided on the design of the building．
A．because
B．before
C．whether
D．unless
The United States ________ its independence from Britain in 1776. [ ]
A. announced
B. expressed
C. declared
D. informed
