A thorough action or activity is one that is done very carefully and in a detailed way so that nothing is forgotten.
We are making a thorough investigation.
我们正在进行彻底的调查。
This very thorough survey goes back to 1784.
这项非常彻底的调查可追溯到1784年。
How thorough is the assessment?
这个评估的彻底程度如何?
Someone who is thorough is always very careful in their work, so that nothing is forgotten.
Martin would be a good judge, I thought. He was calm and thorough.
我想马丁会是个好法官。他既沉着又细心。
Thorough is used to emphasize the large degree or extent of something.
To me, this seemed like a thorough waste of time.
在我看来,这好像完全是浪费时间。