The research team determined that the extra sweetness likely came from grape syrup, added to the champagne before corking.

研究小组确定额外的糖分很可塞封住前加入的萄糖浆。

It's called a plug door, and it basically acts like a bathtub-drain stopper, corking the hole without falling through.

这叫做内嵌式门，功基本上如同浴缸的下水塞子，堵住孔又不会掉进去。