When it rains, it pours:
每当下雨,都会倾盆大雨 ×
祸不单行 √
例句:
A person who could do this must be a bad egg.
能办出这种事的人准是个坏蛋。
A horse of a different color:
不同颜色的马 ×
另一回事 √
例句:
Taking the exam is one thing but passing it is a horse of a different color.
考试是一回事,通过考试又是另一回事。
Call white black and black white:
叫白色为黑色,叫黑色为白色 ×
颠倒黑白、指鹿为马 √
例句:
Don't call white black and black white.
不要颠倒黑白、指鹿为马。