What is the direct object in sentence His father walks with a limp?

There is no direct object in the sentence "His father walks with a limp."

Here's why:

* Direct objects receive the action of the verb. The verb "walks" describes an action the father performs, but there's nothing that the father is directly acting *on*.

* "With a limp" is a prepositional phrase modifying the verb "walks," describing how the father walks.

Let me know if you have any other sentences you'd like to analyze!