单色印刷，其网线角度一般多采用多少角度合适（）.
A.45度
B.90度
C.30度
D.5度
参考答案：A
－How was your final exam, Tom?
－I’m sorry, dad. I failed and only then the importance of studies.
A．I realized
B．I had realized
C．had I realized
D．did I realize
解方程：（x2﹣3x+2）（x2+3x﹣2）=x2（x+3）（x﹣3）
