I was afraid _______ in class, because I thought my classmates might laugh _____ me.
A：to speak; at
B：of speak; at
C：of speaking; to
D：to speak; to
举例说明：现实生活中存在两个变量间的相关关系．
周末，小红和爸爸来到浏阳赤马湖的滑雪场，开始他们的滑雪之旅，到了雪地，小红脱下运动鞋换上了滑雪鞋，这时她对地面的压强会____ （选填“增大”、“减小”或“不变”）；若小红的体重较轻，她和爸爸在水平雪地上滑行时滑板受到的摩擦力分别为F1和F2，则F1____ F2（选填“＞”、“＜”或“=”）
