mount

我帮他骑上了马。

I helped him ___mount the horse.

短暂步行后，导游帮助游客骑上了骡子。

After a short walk, the guide helped the tourists ___mount the mules.

仅仅走了一小段路后，他就不得不帮助他们中的两个人上骡子。

After only a short walk, he had to help two of them to ___mount the mules.