Root diameter of thread
[机] 齿根直径, 螺旋纹底直径
🧩 词语组成解析
root
[rut]
n. 根，根源;原因，本质;祖先;[乐]和弦基音;
vt. 使生根;使固定;根源在于;欢呼，喝彩;
vi. 生根;根除;
of
[əv]
prep. 关于;属于…的;由…制成;
aux. 助动词 [非标准用语、方言] =have [主用于虚拟语气];
thread
[θrɛd]
n. 线;线索;线状物;螺纹;
vt. 穿成串;将（针、线等）穿过…;用…线缝;给…装入（胶片、狭带、绳子）;
🗣️ 情景例句
I've been having a hard time keeping my eyes open
我一直挣扎着要让双眼睁开
It's a pain in the neck having to meet them at the airport.
必须到机场去接他们，真讨厌。
I agree. Which museum would you like to visit?
我同意。你想参观哪个博物馆呢？