$5.$ Agitated vessels are utilized in the gas$-$solid$-$liquid system to enhance $\_\_\_\_\_\_\_\_$ and $\_\_\_\_\_\_\_\_$ transfer rates.

$6.$ The minimum fluidization velocity in fluidized beds is a critical parameter for ensuring the $\_\_\_\_\_\_\_\_$ of particles and the $\_\_\_\_\_\_\_\_$ of the fluid.

$7.$ Bubble column reactors rely on the $\_\_\_\_\_\_\_\_$ of gas through a liquid to facilitate $\_\_\_\_\_\_\_\_$ and reaction processes.

$8.$ Trickle bed reactors are advantageous for their $\_\_\_\_\_\_\_\_$ mass transfer and low $\_\_\_\_\_\_\_\_$ drop characteristics.