Sentence:  I do n't <WSD>know</WSD> whether he was after our rider , who had gone by a minute before , or whether he was simply scouting conditions ; but when he passed us by , a musket roared , and he reared his horse , swung it around , and began to whip it back in the direction from which he had come . 
Meaning of the word marked with <WSD> tags:  be cognizant or aware of a fact or a specific piece of information; possess knowledge or information about