The Arizona Republic once reported that a professor at the University of Arizona was stopped by a highway patrolman while speeding to campus. The officer decided to let him off with the warning, "Slow down and drive safe." The professor felt the need to correct the patrolman. "Officer," he said, "excuse me. You should have said, 'Drive safely.' You said, 'Drive safe'." Whereupon the office promptly wrote him a speeding ticket.
I've lived long enough to know that there are times in life when I need to keep my mouth shut. That prof was being a jerk. He just had to show that he knew grammar. For heaven's sake, don't correct that foreigner's English. He's trying his best. Don't feel like you need to correct every misstatement people make. Don't go around in life setting everyone straight. There may be a time and place when that's appropriate. But when you operate like Christ, you do things humbly.
I love how Paul puts it in 1 Cor. 8:3, 16 (NLT):
Don't think that you better than you really are.
Don't be too proud to enjoy the company of ordinary people.
And don't think you know it all!
Love it!