首先要考虑的就是安全。在野外，很多意外都可能发生。在低海拔地区，危险性虽小得多，但仍须遵循营地选择的基本原则。本页是一米范文爱岗敬业的小编sky帮助大家整理的5...

One night it was almost nine o'clock. I was still doing expements. I met some difficulties.So when I thought I was holding my hair all the time, I wen...