Expressing "inevitably" with 不免 and 难免
不免 and 难免 are the same in translation, but different in usage.
The adverb 不免 
and the adjective 难免 are used to indicate an unavoidable negative situation.
They are placed either before a verb or a verb phrase.
and the adjective 难免 are used to indicate an unavoidable negative situation.
They are placed either before a verb or a verb phrase. Pay attention
不免 and 难免 are usually followed by the auxiliary verbs 会 and 要 .
and 要 .Examples
第一次面试，不免会紧张
It's the first interview, so you'll inevitably feel a little nervous
dì yí cì miànshì, bùmiǎn huì jǐnzhāng
这家公司的实习生难免要做一些打杂的事
There's no way for the interns at this firm to avoid doing some menial work
zhè jiā gōngsī de shíxíshēng nánmiǎn yào zuò yìxiē dǎzá de shì
难免 can be followed by the negative particle "not", whereas 不免 cannot.
Examples
生活中难免不会遇到不顺心的事
Life is not without its ups and downs
shēnghuó zhōng nánmiǎn bú huì yùdào bú shùnxīn de shì
我们对这个领域还不熟悉，研究难免没有遗漏之处
This area is new to us so our research inevitably leaves much to be desired.
wǒmen duì zhè ge lǐngyù hái bù shúxī, yánjiū nánmiǎn méi yǒu yílòu zhī chù
难免 can be used as part of the structure 是…的 , whereas 不免 cannot.
, whereas 不免 cannot.Examples
这些过错是难免的
These mistakes are inevitable
zhèxiē guòcuò shì nánmiǎn de
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