原文标题：

Ageing reversal: scientists rejuvenaye tissues in middle-aged mice 科学家新疗法让中年老鼠“重返青春”

每日英语：

1 you could cut the atmosphere with a knife

英文释义：

used to say that the emotional tension,

embarrassment,etc. shared by a group of people is very great

气氛非常紧张；局面非常尴尬；剑拔弩张

例句：

When John came in with his new girlfriend,you could have cut the atmosphere with a knife.

约翰带着新女友进来时，气氛极其紧张。

2 take attendance

英文释义：

check who is present and who is not present at a place and mark this information on a list of names点名

例句：

The teacher took attendance at the beginning of every class.

每次一上课老师都要点名。

3 have sth on good authority

英文释义：

be able to believe sth because you trust the person who gave you the information

有可靠的根据相信

例句：

I have it on good authority that the chairman is going to resign.

董事长要辞职了，我这个消息是有根有据的。