来 (lái) comes after a length of time like a number of days or years, etc to mean “ever since”: length of time + 来: – 几个月来，我认识了很多朋友。jǐ gè yuè lái, wǒ rènshíle hěnduō péngyǒu. Over the past few months, I have made a lot of friends. – 结婚一年来，他们没吵过架。jiéhūn yī niánlái, tāmen méi chǎoguò jià. Over their one year of marriage, they have not had an argument.