"They try to win."
Translation:Họ cố gắng để thắng.
I disagree. Cố gắng is to try. Thử is more like attempt. Example, "I want to try that food" is "tôi muốn thử đồ ăn đó" but if you wanted to say "try to listen" it would sound weird to say "thử nghe nha", the better way would be "cố gắng nghe nha!" Thử is like trying something new. Cố gắng implies effort.