• Populations fluctuate in size.
• The temperature fluctuates .
• The pointer oscillates with respect to the centre of the scale.
• The atoms oscillate ( or vibrate ).
• The prices vary ( or fluctuate ).
• The conveyor vibrates .
• In the steady state, c oscillates ( or fluctuates , or varies ) between upper and lower limiting values.
• The controlled variable will oscillate forever about the desired steady-state value.