He is doing squats to strengthen his rectus femoris muscle.

He is doing special exercises to strengthen his superior rectus muscle.

He is doing special exercises to strengthen the lateral rectus muscle.

He is doing a special exercise to strengthen his inferior rectus muscle.

He is doing special exercises to strengthen his medial rectus muscle.

The rectus capitis anterior muscle is part of the neck muscles, helping to bend the head forward.

He turned thirty years old.

This picture is fixed to the frame.

This plant needs oxygen to perform photosynthesis.

In this story, Zuan is the protagonist, and his adventure continues.