Idioms are a pain in the

Idioms are a pain in the
Idioms are a pain in the

Idioms are a pain in the
be a pain in the neck的意思是“非常恼人的、讨厌的”.
我认为这句话的意思是“(在学习语言时)成语、惯用语很令人烦恼”,或说“很难”.

a pain in the neck意思是"讨厌的家伙, 可恶的家伙, 使人厌烦的责任, 使人厌烦的义务".
Idioms are a pain in the neck