你意下如何?英语怎么说？

最简单的就是How about you?

what are you up for ?
what are you in the mood for ?
how do you feel about that?
what about you ?
不太严格的话 应该都可以 最好你给出语境 才方便决定怎么说。。。

如果是在问对方关于对某事的观点可以说:Do you agree?
Your opinion? What's your point of view? What do you think about it?

若是问对某物的看法可以说：Match your style? Is it ok?

当然前面的那种的后两种说法也适合对第二种含义的提问．
若是很随意就可以直接用简单的句子了，不必那么死板．其实外国人很少这样说What'之类的老土问话的．

希望我的答案可以满足你的问意．帮助到你．

what do u think?
what do u say?
一般非书面的说法这俩比较常用，且是最简单的
若要花哨一点的 别人答案里可见

what do you mean?

What do you think?/What do you mean?