ــــ أَكَلْتُ الـتُّـفَاحَ I did not eat the apple

ــــ شَرِبْتُ الـمَاءَ I did not drink the water

ــــ فَهِمْتُ الـمُعَلِّمَ I did not understand the teacher

ما كَتَبْتُ الدرسَ ولا حَفِظْتُهُ I did not write the lesson nor did I memorize it

I can use the particle لا because there is:

لا قَدَرَ اللُهُ May God forbid

I can use the particle لا because there is:

ما رَأَيْتُ الرّئيسَ ولا سَـمِعْتُ عنه شَيْئًا من قبلٍ I have neither seen the president nor heard anything about him before

﴿ فَلَا صَدَّقَ وَلَا صَلَّى ﴾