?碰到

... come up发生；走上前来；（时间）快到 come up against碰到（困难） come up to达到（高度、程度）；符合 ...

?遭遇

... come up 走近;长出,发芽;被提出来 come up against 遭遇(困难或反对);迎击,与…相违背 come up with 想出(计划,答案,回答等),提出 ...

?遭到

... come up 抬头；上来；上升 come up against 遭到(困难、反对等)，遇到 come up to 走近，靠近 ...