Ehl
[医][=effective half-life(of radioactive substances)]（放射性物质的）有效半衰期
🗣️ 情景例句
You didn't put film in the camera, silly!
笨蛋，摄影机里没有放胶卷。
A good book is a best friend who never turns his back upon us.
一本好书，莫逆之交。
How do you like China?
你们喜欢中国吗？