This butterfly valve is used to control the flow of fluid.

He explained in detail about the structure of the sphenoid bone.

He drew a straight line using a T-square.

She is learning the grammar of the present progressive form.

He is doing special exercises to strengthen his flexor digitorum profundus.

He always keeps in mind the phrase 'If one learns without thinking, it is a waste.'

This shape is a parallelogram.

This shape is a parallelogram.