1. Riding was a novelty to her.
    骑马对她来说是件新鲜事。

2. One day while we are riding the subway, I ask, “What are the reasons you picked me to watch Sam?”
    有一天，在我们乘坐地铁时，我问："是什么原因让你选择我来照看山姆？"

3. Later it crossed the Channel, riding smoothly over the waves, which presented no problem.
    后来气垫船跨越英吉利海峡，平衡地在波浪上方行驶，波浪不再产生阻力。

4. I think riding a bicycle is preferable to walking.
    我认为骑自行车比走路更可取。

5. Fortunately for me, as I was wondering what to do next, there appeared on the horizon a man on horseback, riding in my direction.
    不过，我是幸运的，正当我走投无路之时，从天边出现一个骑马的人向我骑来。