she couldn’t help feeling sad and tears would run down her c

she couldn't help feeling sad and tears would run down her cheeks( )she came back to
the ruins where her home was once built. 为什么答案是for the first time ?为什么不能用at the moment

翻译：当她来到这片废墟上时——她的家原来就建在这里——她不禁感到一阵悲伤,第一次留下了眼泪.
不能用at that moment的原因是:the moment 本身就是连词了,at 是多余的.
例如：please give him this thing the moment you see him.你看见他的时候请把这东西给他.
遗失的meng