I do solemnly promise and declare that I would not open or delay or cause to be forced to ope or delay any letter or anything by posed.

我庄严地承诺绝不擅自打开或延迟，或者在逼迫下打开或延迟任何信件或邮寄的物品。

youdao

I do solemnly promise and declare that I will not open, or delay, or cause or suffer to be opened or delayed, any letter or anything sent by post.

我庄严承诺并且宣誓，我不会擅自打开或延误，或致使别人或被迫去打开或者延误任何信件，或者任何其它邮寄来的邮件。

youdao

"I'll write," I promise solemnly.

我庄严地发誓会给他们写信。

youdao