‎The sky is clear; the stars are twinkling.​

中国大学MOOC: The sky is clear; the stars are twinkling.

The relief grade of fluorite is : ( ) A: Negative high relief B: Positive low relief C: Positive median relief D: Twinkling

The relief grade of muscovite is : ( ) A: Negative high relief B: Positive low relief C: Positive median relief D: Twinkling