They dragged him foot by foot through the hall of the jail.

他们拖着他一步一步地穿过监狱的大厅。

Then he crept forward foot by foot until he was almost upon them, when with a sudden spring he darted into their midst.

他一步一步向前爬行，他几乎要抓住他们，他突然一跃而起钻入他们的巢穴。