In Arabic, we use either ما or لم to negate the verb in past. for example:
(هل قَرَأَتَ الكِتابَ؟...( لا ما قَرَأْتُ الكتاب
which equals =
(لا، لَمْ أَقْرَأْ الكتاب)
(have you red the book? .. No, I haven't read it)
Notice that after لَمْ. we use the verb in present form although it's past in meaning.
when should we we use لَمَا as an alternative to لمْ , but the meaning is a little bit different.
هل قَرَأَتَ الكِتابَ؟...لا، لم أَقْرَأ الكتاب (that means you didn't read it or haven't read it)
هل قَرَأَتَ الكِتابَ؟...لا، لمَّا أَقْرَأ الكتاب ( that means you haven't read it yet , but it's expected that you will read it )
هل ذّهّبْتَ إلى الطَّبيبِ أمْسِ؟ ... لا ، لم أذْهَبْ إلى الطبيب أمس
هل ذهبت إلى الطبيب؟ ... لا، لمَّا أذْهَبْ إلى الطبيب ( i n this sentence, you possibly or probably will go )
Sometimes we use the word: بَعْدُ which means yet.
هل سَافَرْتَ إلى مِصْرَ ؟ ... لا، لَمَّا أُسافر إلى مِصر بَعْدُ
Have you traveled to Egypt? ... No. I haven't traveled to Egypt yet
( that means you might have told a friend that you have the intention to travel to Egypt and after a while when he had met you, he asked you that question and you used لَمّا because you still have the intention to go there.
