Don't teach your grandmother to suck eggs.是什么意思？

Don't teach your grandmother to suck eggs.

休要班门弄斧。

teach

vt. 教，教导，训练，教授；vi. 教书；

例句
Different schools teach different types of syllabus, from the highly academic to the broadly vocational.
不同的学校有不同的教学计划，从高度学术的到普通职业教育的，不一而足。

your

pron. 你的，你们的，尊，玉，乃；

例句
I think there's something a little peculiar about the results of your test.
我认为你的化验结果有点不对劲。

grandmother

n. （外）祖母，老奶奶，女祖先；vt. 当…的祖母；vi. 当祖母；

例句
The newspaper contacted his grandmother to trace his present address, and later doorstepped him at his home.
报纸联系了他祖母，查到了他现在的住址后便前往登门采访。

to

prep. 向，朝着，到，关于，属于；adv. 朝一个方向的，到某种状态，关闭；

例句
I suggest you leave it to an expert...
我建议你把它留给专家来解决。

suck

vt. 吮吸，吸入，卷进入，吸取；vi. 舐，吮吸，吸入，通过吸吮的动作产生声音，<俚>巴结；n. 吮吸，吸力，吸入物；

例句
Good writers suck in what they see of the world, recreating their own universe on the page...
优秀的作家从他们眼中的世界汲取体验，然后在纸上重塑自己的天地。

eggs

n. 卵( egg的名词复数 )，蛋，卵子，卵细胞；

例句
Place the eggs and sugar in a large basin.
把鸡蛋和糖放在一个大碗里。