## 每日一词：obdurate（转自 韦氏词典）

Merriam-Webster’s Word of the Day for December 30, 2018 is:

1 a : stubbornly persistent in wrongdoing

b : hardened in feelings

2 : resistant to persuasion or softening influences

Examples:

Obdurate lawmakers on both sides of the aisle have made it difficult for the state legislature to get anything done this term.

“The emigrants were strong-willed and obdurate. Their dreams were based as much on imagination as on the writings and maps of land speculators and entrepreneurs.” — Edward Cuddihy, The Buffalo (New York) News, 1 Oct. 2017

Did you know?

When you are confronted with someone obdurate, you may end up feeling dour. During the encounter, you may find that you need to be durable to keep your sanity intact. Maybe you will find such situations less stressful in the future if you can face them knowing that the words obdurate, dour, and durable are etymological kissing cousins. All of those words trace back to the Latin adjective durus, which means “hard.” This adjective can still be found in dura mater, the name for the tough fibrous material that surrounds the brain and spinal cord, which comes from a Medieval Latin phrase meaning, literally, “hard mother.”

Lake桑

December 30, 2018 at 01:00PM

TL;DR

## 二、学生测定空气成分

### 现象

$\rm P+O_2 \overset{Fire}{\longrightarrow} P_2O_5$

• 污染小
• 误差小

Lake桑

2018.12.30