If it has a correct gender specific noun. If its singular or plural. Irregular verbs. The fact there is two different verbs. Past tense or current. Verb of change. Spanish prepositions. Direct and indirect pronouns. The word gustar.
Answer:
its INCORRECT
Explanation:
because it should be: los estudiantes ESTAN jugando tenis.
NOT
los estudiantes ESTA jugando tenis.
Siempre is always in spanish