一时语塞

My mother, who is never speechless, was speechless.

我那从来都是滔滔不绝的母亲，一时语塞了。

It was the only one that momentarily stumped me for an appropriate answer.

它是唯一让我一时语塞、找不到合适答案的问题。

I was speechless.

我一时语塞。

Alfred did not know what to say, _and_tried to keep his eyes from meeting the eyes of his boss. After a few moments, he put his hand into his pockets_and_took out the things he had stolen.

艾尔弗雷德一时语塞，努力避开老板的目光、过了一会儿，他把手伸进口袋，把偷的东西拿了出来。

Of course if there is a question which you are not expected to know the answer to, or if you are genuinely stuck, don´t make things up or try to bluff your way through.

当然了，如果出现了一个你不知道如何回答的问题、或者你一时语塞，也不要编造事实或试图蒙混过关。