اعراب عليك الّا تهمل دروسك

In the sentence “عليك ألا تهمل دروسك”, “عليك” is a verb that means “be obligated”, with an implied subject of “أنتَ”. “ألا” is a non-expressive particle with no grammatical function. “تهمل” is a present verb in the second person singular form, with an implied subject of “أنت”. “دروسك” is the direct object in the accusative case, with a marker of “فتحة” on the final letter. The “ك” at the end is a pronoun in the genitive case. The sentence overall means “You must not neglect your lessons”.