If the birds have not flown for three years, they will soar into the clouds. If they have not sung for three years, their songs will take everyone bysurprise.
三年不蜚，蜚将冲天；三年不鸣，鸣将惊人。
《新英汉大辞典》
2
They reduced the odds that a predator would take us bysurprise or that we'd overlook a nearby source of food.
这样一来，我们被对手突袭的机会减小了，也不会错过触手可及的食物。
3
How it happens will take you completely bysurprise.