挠痒的英文：
to scratch an itch

参考例句：

The mongrel presented his muzzle for scratching.
这只杂种狗探出口鼻挠痒。

scratch是什么意思：
v. 抓破；擦伤；搔痒；抓，扒；发出刮擦声；乱涂乱画；勉强糊口；退出比赛
n. 搔，刮；抓痕，擦痕；乱涂，乱画；刮擦声
adj. 打草稿用的；东拼西凑的；平等比赛的

This is absolutely a scratch.
这完全就是一通乱写。

This is a scratch of the pen.
这是大笔一挥，匆促而随便写就的。

This is a scratch meal.
这是顿现凑成的饭菜。

This is a scratch team.
这是支临时凑起来的球队。

toe the scratch
用脚尖踩在起跑线上|遵守规则|承担责任

itch是什么意思：
n. 痒；渴望；热望
v. 发痒；渴望；热望

Scratch where it itches.
搔痒。

Kathy has an itch to travel.
凯茜渴望出去旅行。

I was itching to get involved.
我渴望参与。

The general was itching for a fight.
将军盼着打一仗。

He is itching after fame.
他热切地追求名誉。