TOEFL单词短语学习：

erosion n. 侵蚀，腐蚀 (noun): wearing away of the soil by wind and water
- Erosion is often a natural process by which many geological formations are created.

breathtaking adj. 惊人的；惊险的；令人激动的 (adjective): incredible, awesome, amazing
- The scenic views of the valley were breathtaking.

strenuous adj. 紧张的；费力的；奋发的；艰苦的；热烈的 (adjective): physically difficult
- We took a very strenuous hike that lasted all day, and I'm exhausted.

wash n. 洗涤；洗的衣服；化妆水；冲积物 (noun): a dry stream bed
- We followed the wash for about a mile until we reached the mouth of the canyon.

leave word 留言 (verb): notify or inform
- She didn't leave word where she would be traveling, and now her family is really worried.

sturdy adj. 坚定的；强健的；健全的 (adjective): strong
- You need to wear sturdy hiking boots for this trip because we will be going through some rough terrain.

dehydrated adj. 脱水的 (adjective): suffer from lack of water
- The lost hiker was extremely dehydrated when she was found wandering in the desert.