他们一定累了，因为他们已经连续工作5小时了。的翻译：They must be tired because they had 5 hours of continuous work. 什么意思？中文翻译英文，英文翻译中文，怎么说？

青云英语翻译

They must be tired, because they have continuous working hours.

They must be tired because they had 5 hours of continuous work.

They have been certainly tired, because they already the continuous working for 5 hours.

They must be tired of it, because they have been working continuously for 5 hours.

They must be tired because they had 5 hours of continuous work.