· be in a rut千篇一律，一筹莫展
His life is in a rut. Office, library, and home are the three places he goes everyday. It is time he had a holiday for a change.
· play it safe小心谨慎
Our car works very well. But to play it safe, we will bring a spare tire.
· safe and sound安全无事
He came back from the battlefield safe and sound.
· the salt of the earth好心肠的人，没有坏心眼的人
The taxi driver who saved the drowning boy from the river is the salt of the earth.
· take something with a grain of salt听话打折扣，不能轻信
He is a braggart. Take his words with a grain of salt.
· tip the scales扭转局势
In the boxing ring, the two sides were evenly matched. But the short break seemed to tip the scales in favor of the boxer in red.
· throw someone off the scent转移某人的视线
The murder wrote a last letter for the victim and left it in the site, hoping to throw the police off the scent.
· start from scratch从零开始，白手起家
There are so many spelling mistakes. I have to write it again from scratch.
· talk sense into someone开导某人
I've tired to talk sense into him, but he still chose to work in the countryside.
· an open sesame法宝，秘诀，关键
Having connections with VIPs is not an open sesame to success.
· the lion's share最大的一份，绝大多数
He designed the most important part of the machine. So he deserves the lion's share of the award.
· the black sheep of the family有辱门楣的人
He lost everything in gabling and was called the black sheep of the family by this relatives.

更多学习：日常英语口语