come up against造句怎么写

But if we were to thrust westward, we would come up against the Kan River and have no room for expansion after the battle.

And the places where these plates come up against one another are called faults in the earth's crust.

Some people say, "Once you have a job, you'll come up against the urgent problem of making a living. How can you manage to find time to study? Even if you want to, will it be possible with no library or laboratory available?"