富貴竹葉片變黃

It has happened to me before. Do not use tap water freshly from the tap to water it. Chlorine in the water will cause the leaves to go yellow and wilt.
My plant was grown in water. So, I can only tell you from my experience. Take the plant out, vigorously clean it in a bucket of water which you have stood aside for a few days. Strip off the yellow leaves altogether from the stem. Then place it back into the vase with around 6" of water.
Do not add any fertilizer until it has been stable.
No need to change water too frequent. But don't let it dry up.
Good Luck.

原因係缺鐵囉! 你可以去花店買支營養水，就ｏｋ啦！