solemnly

ad. 严肃地, 庄严地

As God is my witness (ie I solemnly swear), that's the truth!

上帝为我作证, 一切属实!

On Saturday morning my father solemnly dispensed pocket money to each of the children.

星期六上午我父亲郑重其事地给每个孩子发零花钱.