I couldn't help crying.
忍不住哭了.
"between astonishment and joy,she couldn't help bursting into tears."
"她惊喜交集,禁不住放声大哭起来."
‘can i have a drink?’ ‘help yourself!’
“ 可以喝一杯吗?”“请随意.”
help yourself to some fish.
请自己动手吃点鱼吧.