Make a mountain out of a molehill:
一座小丘说成一座山 ×
小题大做 √
例句：
She shouted at him angrily for being five minutes late, but she really made a mountain out of a molehill.
因为他迟到了五分钟，她很生气地对他大喊。她真是小题大做。
Break one's back:
背都打碎 ×
非常辛苦地工作 √
例句：
Working as a consultant in this company will break your back.
在这间咨询公司上班非常辛苦。
Back the wrong horse:
支持错的马 ×
押错宝，选错人 √
例句：
He rarely backs the wrong horse when it comes to investing in stocks.
他在炒股票时很少看走眼。
