树枝在风中摩擦发出刺耳的声音。

The branches ___gnarl loudly as they rub together in the wind.

当他靠近时，那只狗开始发出低沉的咆哮声。

The dog started to ___gnarl when he got too close.

别总是抱怨工作，做点实事吧。

Stop ___grumbling about your job and get some work done.