i will only explain it （once ）为什么explain it 后面用once而不用one

i will only explain it （once ）为什么explain it 后面用once而不用one I will only I will only a little I will have time to explain your stand husband,I will always only love I will only yourself thought life! Now,I will only make you very I will only love my wife forever I will be your only sunshine I will explain to you why I like it.为何不能省略to? 英语翻译歌词如下;I worry I weigh three times my body I worry I throw my fear around But this morning,there a calm I can explain The rock candy's melted,only diamonds now remain By the time I recognize this moment This moment will be gone But You only will then understand how that,i will love I dont understand you.Please explain.Does it means that you will I learned to spare the same cherish,what people will choose to explain? if i love you,i will only remember you Can only exist between us to explain? 英语选择题（语法）1 I can't understand it.Will you please _____once more?A explain that word B repeat that word C explain us that word D explain that word for us. I can't understand it,will you please _____ once more?A.explain that word B.repeat that word C.explain us that word D.explain that word for us为什么D不对A和C有什么区别