Hi, if you're new to learning languages, then please see A List of Common Linguistic Terms to learn what words like "accusative" and "strong verbs" mean. You should know that in Old English, verbs changed (we say that we "conjugate" verbs when we change them) a lot more than in Modern English. In Modern English, we usually add "-s" to third person singular verbs; that means that verbs used with words like "he", "she" or "it" add "-s", for example, we say "I sing" but "he sings". See? We added an "-s" to the end of the verb when we used it with "he", but we didn't when we used it with "I".