fair-weather friend
noun [ C usually singular ] disapproving uk/ˌfeə.weð.ə ˈfrend/ us/ˌfer.weð.ɚ ˈfrend/
酒肉朋友，不能共患难的朋友
someone who is a good friend when it is easy to be one and who stops being one when you are having problems
英汉双解词典收录81607条英汉双解翻译词条，基本涵盖了全部常用单词的读音、翻译及用法，是英语学习的有利工具。