Did you know that some Russian particles have short forms? These forms are widely used in literature, especially in poetry, and sometimes in colloquial speech. The most widely used short particles are: ль (ли), б (бы) and ж (же). However, the particle ли is never used in its short form in indirect questions.
Тебе льне знать, как сложно работать с детьми. You should know how difficult it is to work with children.
Если б я могла поехать сейчас в отпуск! If I only could go on holiday now!
Что ж ты не сделал ничего? Why didn’t you do anything?