TO COME ACROSS smth/smb
To meet or find something by chance or accident

EXAMPLES
•I CAME ACROSS an old English dictionary 
 in the library.

•You have never COME ACROSS anyone 
 more clever than me.

•We have COME ACROSS a serious problem that we need to solve ASAP.

QUESTIONS TO ANSWER
•What would you do if you CAME ACROSS 
 an alien?

•What do you do with the money that you COME ACROSS in your pockets?

•Are you afraid to COME ACROSS your Ex?