Как правильно написать She plays the piano.(sometimes) She is very busy.( usually)

Правильно так:

She sometimes plays the piano.
She is usually very busy.

Объяснение:

В английском наречия частотности, такие как sometimes, usually, often, always, never, обычно ставятся:

1. Перед смысловым глаголом

   • She sometimes plays the piano.

   • He often reads in the evening.

2. После глагола to be

   • She is usually very busy.

   • They are always late.

Поэтому:

• She plays the piano. (sometimes) → She sometimes plays the piano.

• She is very busy. (usually) → She is usually very busy.