例句：However, scientists have found on-off relationships like this one are not only emotionally draining for everyone involved, but can also damage your health.
翻译：然而，科学家发现像这样（情侣）分分合合的关系，不但让你感情上精疲力竭，而且会损坏你的身体。
on是开，off是关，这里 on-off relationship就非常形象生动地描绘了经常分分合合的关系，这里另外一个单词drain,意思是把水排干，这个词也常用做耗尽资源，耗尽心血的意思。
