The internal urethral sphincter plays a crucial role in controlling the flow of urine.

The urethral sphincter is a muscle that controls the flow of urine.

She was hiding the sadness concealed within her smile.

He will succeed sooner or later.

The external urethral sphincter is an important muscle for controlling the excretion of urine.

The flow of the river is very calm.

He worked hard to accomplish his goals.

His role is the team leader.

Health is very important.

His opinion is very important.