建筑安全技术
推土机上坡坡度不得大于( ),下坡坡度不得大于( )。
A.20°;30°
B.30°;20°
C.35°;25°
D.25°;35°
参考答案:D
Who is it______have the most important role to play in stopping Yellow River erosion?
A,who B.that C.which D.whom
概述市场营销调研的主要方法?