There are different particles used for negation in Arabic.

(لا) is used to negate present tense verbs. It must be used immediately before the verb, e.g.

لا أذهب إلى عملي بالسيارة.

“I do not go to my work by car.”

أصدقائي لا يحبون السفر معي.

“My friends do not like travelling with me.”

(ما) is used to negate past tense verbs, and it must be directly followed by the past tense verb, e.g.

ما قرأت هذا الكتاب.

“I did not read this book.”

كيف ما عرفتم هذا الخبر؟

“How come you did not know the news?”

(لم) is also used to negate past tense verbs; however, it must be followed by the present form of the verb, e.g.

لم أقرأ هذا الكتاب.

“I did not read this book.”

كيف لم تعرفوا هذا الخبر؟

“How come you did not know the news?”

(لن) is used to negate future verbs, and it must be followed by the present form of the verb, e.g.

لن أحضر محاضرة الغد لأنني سأسافر لزيارة والدتي.

“I will not attend tomorrow’s lecture because I will travel to visit my mother.”

ستقابلون المدير ولكنكم لن تعرفوا القرار.

“You will meet the manager, but you will not know the decision.”

Nominal sentences are negated using (ليس) which has to be conjugated in the appropriate way according to the subject of the nominal sentence, e.g.

ليس هذا كتابي.

“This is not my book.”

لستُ من هذه المدينة.

“I am not from this city.”

خالد ليس أخي، هو صديقي.

“Khaled is not my brother; he is my friend.”