对列表项ul块设置margin的外上边距为0作用是去掉ul默认外上边距对层的影响

A、绝对化的要求
B、过分概括化
C、糟糕至极
D、不懂得放弃

A、a long story about the American frontiers or cowboys
B、a story with unbelievable elements, related as if it were true and factual
C、a story with intricate plot and a fairytale-like ending
D、a story presented in refined language of the upper class

A.＜1800r/min
B.＜1500r/min
C.＜900r/min
D.＜500r/min