[" I shave every day,but my beard "],[" stays the same.What am I? "]

I am sure my classmates will bear away my statement.

I am a fraction.My numerator is a difference of 3 and 2 and my denominator is the sum of 2 and 3. Who am I?

I am the universal food provider. Every food chain starts from me. Who am I?

I am always the companian of doctor. Doctors can hear the heart beat with my help. Who am I?