n. the action of one object or surface moving against another; the resistance of one surface to another surface or substance moving over or through it
A: gravity
B: friction
C: hydrogen
D: governor
A: gravity
B: friction
C: hydrogen
D: governor
举一反三
- Among the following forces, there are surface force （ ） A: gravity B: friction C: pressure D: surface tension E: inertial force
- When moving from one idea to another, people should remember to __________.
- Words or phrases that indicate when a speaker has completed one thought and is moving on to another are called __________.
- The volume of the water flow and the change in _____ from one point to another determine the amount of available energy in moving water.
- They compete____ . A: against one another B: the one against the other C: each against the other D: against each one