Student or Learner
1. Concorde can travel at twice the speed of - sound.
2.family needs to have an understanding of what the puppy needs.
3.It serves an excellent "California-Mediterranean" menu.
I want to know why the before speed and no article before sound in sentence 1
and why an before understanding in sentence 2
and why an before excellent menu in sentence 3
I want to know if menu, speed sound and understanding are countable or non countable nouns and what is the rules.