Sincethat和sincethen是一样的吗为什么

Sincethat释义：

因为这

例句：

He's borne me a grudge ever since that day.

从那一天起他便对我怀恨在心。

sincethen释义：

自

例句：

Sincethen the 35-year-old's appearance has fluctuated from being skinny tovery skinny.

从那时起，现年35岁的贝嫂就不断地在很瘦和瘦的皮包骨之间波动。