We usually ... tennis in the park.
plays
play
are playing

Відповідь:

We usually play tennis in the park

If you have word "usually", you need to use present simple. Present simple is formed this way:

+: (we, you, they, I) - verb, (he, she, it) - verb + s

-: (we, you, they, I) - don`t + verb, (he, she, it) - doesn`t + verb

?: (we, you, they, I) - do + (we, you, they, I) + verb, (he, she, it) - does + (he, she, it) + verb

Is it clear right now?))