необходим для

• Consideration of the ordered array of atoms or ions is basic to an understanding of the results.

• Complex numbers are necessary to the mathematical treatment.

• Artificial ventilation is required to maintain a normal atmosphere.

• The presence of an inert strand is requisite for these processes.

• Considerations of phase equilibria are essential to (or necessary for) an understanding of any mass-transfer process.

• Calcium is also essential in many biological functions of the vertebrates.

• Carbon dioxide is essential to synthesis.

• Minute in amount but indispensable for life are the hormones and vitamins.