Reciting only the verses that one knows?

No File Exists
Check below answers in case you are looking for other related questions:
Reciting another soorah before al-Faatihah goes against the teaching of the Prophet (peace and blessings of Allaah be upon him)
Sending blessings upon the Prophet (blessings and peace of Allaah be upon him) when he is mentioned in obligatory and naafil prayers

No File Exists
Related Answers:
He recites the soorah after al-Faatihah quietly so that the congregation can recite al-Faatihah
He used not to recite al-Faatihah behind the imam; should he repeat those prayers?
Can’t recall part of a verse during prayer
Reciting another soorah before al-Faatihah goes against the teaching of the Prophet (peace and blessings of Allaah be upon him)
Sending blessings upon the Prophet (blessings and peace of Allaah be upon him) when he is mentioned in obligatory and naafil prayers

Recommended answers for you:
Ruling on drawing animate beings
Disturbed by Waswas (Whispers From the Shaytan) and Evil Thoughts
Questions about zakaah on jewellery and how it should be paid and who should pay it
He has a number of questions about zakat al-fitr
Al Sunnan Al Rawatib (Sunnah Prayers associated with Fardh Prayers)