兹证明：上述货物全部收讫，集装箱，箱封和货物外包装完好，特此签收。

We declare that the above mentioned goods is well received, container, seal and the outside of packing is(are) in good condition.

炉子封了吗？

Have you banked up the fire?

问题是人们会有许多许多的邮件，可能是每天几十封甚至上百封。

The problem is just that people get a lot of emails. Maybe dozens or hundreds each day.

我想寄封挂号信。

I'd like to send a letter by registered mall.

农场被大雪封住了。

The farm became snowbound.