马克思说：“美洲的发现、绕过非洲的航行，给新兴的资产阶级开辟了新天地。东印度和中国的市场、美洲的殖民化、对殖民地的贸易、交换手段和一般商品的增加，使商业、航海业和工业空前高涨，因而使正在崩溃的封建社会内部的革命因素迅速发展。”这些“革命因素的发展”的最重要的作用是

— Yes, they are.

如图，已知直线a∥b，且a与b之间的距离为4，点A到直线a的距离为2，点B到直线b的距离为3，AB=$2\sqrt{30}$．试在直线a上找一点M，在直线b上找一点N，满足MN⊥a且AM+MN+NB的长度和最短，则此时AM+NB=(    )

根据句意及汉语提示填空。
____ We can't ____ ____ ____（习惯）the weather here because the wind is always strong.
____ I'll help you, ____ ____（即使）I don't sleep for a night.
____ I would like more time to _____ this problem _____ (仔细考虑).
____ You can ____ us ____ (打电话给……) when you get to Shanghai. We will meet you.
____ At the age of 5, my father ______ _____ _____ (对……感到满意) my good results at school.