1·If you are sad, please tell me.
如果你伤心了，请告诉我。
2·If you are sad, please forget me .
你是想说请忘记我吧？
3·If you are sad, that affects my own mood.
如果你伤心，我的心情会受到影响。
4·If you are sad, because it is your mind activities.
如果你很悲伤，原因也是你的心灵活动。
5·If you are sad because of me, then please forget me.
如果你因我而悲伤，那就请你忘了我。
6·If you are sad, a good laugh will make you feel better.
如果你很难过，开怀大笑会使你感觉好一点。
7·If you are sad, it becomes difficult for the other to move away.
如果你悲伤，也会使他人很难离开。
8·If you shed tears, wet always my face, if you are sad, always cry my heart.
你若流泪，湿的总是我的脸，你若悲伤，哭的总是我的心。
9·If you are sad about seeing her go, there are three other pandas at the zoo.
如果你对她离去感到悲伤，动物园里还有三只熊猫。
10·If you are sad at the moment, even it was happy in your mind, but you are dolorous. So.
如果心情是忧郁的话，即使回忆的内容是那么的开心，也是忧伤的。