题目

阅读理解 Sahara Marathon 2021-Around the World The Sahara Marathon is organized by the Saharawi Ministry of Youth and Sports and a group of volunteers from different countries. During the last twenty years, thousands of runners from all continents have traveled to the Algerian desert to live the experience provided by this race and to connect with refugee (难民) families. In this unique race of 2021, the experience will be different. The race will be held in a virtual(虚拟的) way and the ·contributions collected through the event will go to the most needy families in the Saharawi Ca1．冰壶运动员的鞋底一只是塑料的，另一只是橡胶的．他滑行时，橡胶底的鞋比塑料底的鞋受到摩擦力大．如图他用b脚蹬冰面后，只用a脚向右滑行，可以确定的是（　　）A．a鞋的鞋底是橡胶底B．b鞋的鞋底是橡胶底C．a鞋底滑行时惯性小D．b鞋底滑行时惯性大