4-2。which is the best material for heat insulation？（ ）
A: water
B: cotton
C: vacuum
A: water
B: cotton
C: vacuum
举一反三
- Which of the following is not a function of modern lubricants A: Reduced friction B: Heat insulation C: Sealing D: Heat dissipation
- The thermal conductivity of the insulation material outside the tube is 0.08W/m.K. The convection heat transfer coefficient outside the tube is 8W/m2.K. What is the critical insulation diameter of the tube? A: 20m B: 2m C: 0.2m D: 0.02m
- Which of the following titles best describes the passage as a whole A: The Vacuum: Its Fluctuations and Decay. B: The Vacuum: Its Creation and Instability. C: The Vacuum: A state of Absence. D: Particles That materialize in the Vacuum.
- Which is NOT the characteristic of “COTTON”？ A: low absorbency B: good heat conductivity C: soft hand D: tend to wrinkle
- Which of the following nouns are material nouns? ( ) A: coffee B: tree C: water D: honey