Material through which water flows is permeable. This material can be either natural or artificial. Naturally permeable material can be clean sand and gravel for example, or a sandstone and in the latter case the sandstone can have both porosity which is not synonymous with permeability as the pores must be connected to be permeable. An impermeable membrane could be used to line ditches for example to prevent leakage near mines.
The organs are known as Vestigial organs. The evolution from land-dwelling animal to the marine animals has led whales as well as dolphins, to lose hind limbs. The pelvic and leg bone serves no purpose in them and just provide the anchorage to muscles
For the first question-a bicep is a large muscle in the upper arm which flexes the arm and forearm, a tricep is a large muscle at the back of the upper arm and a deltoid is a thick triangular muscle covering the shoulder joint and used for raising the arm away from the body.
"<span>Based on variability, the costs has been classified into three categories, they are fixed, variable and semi variable. </span>Fixed costs<span>, as its name suggests, is fixed in total i.e. irrespective of the number of output produced. </span>Variable costs<span> vary with the number of output produced. </span>Semi-variable<span> is the type of costs, which have the characteristics of both fixed costs and variable costs".</span><span>
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