不可

bù kě piān fèi

不可偏废

not to overlook either of the two

quē yī bù kě

缺一不可。

Neither one shall be neglected.

bù kě bì miǎn

不可避免

unavoidable

fēi cǐ bù kě

非此不可。

It must be so.

wǒ rèn wéi fēi xià yǔ bù kě

我认为非下雨不可。

I think it's going to rain.

jīn tiān zhè ge huì fēi cháng zhòng yào wǒ fēi qù bù kě

今天这个会非常重要，我非去不可。

Today's meeting is very important, and I cannot afford not to attend.