El viernes hay un examen sobre las formas irregulares de “ser”.
You must use a definite article (<u>masculine</u> and <u>singular</u><u> </u>to agree with the accompanying noun) is "el".
The article is definite because it speaks of exactly one Friday.
<h3><em><u>MissSpanish</u></em></h3>
Teniamos porque los otros son tiempo pasado
I love breakfast, especially fries.