Apersonal business letter may be written by

a personal business letter may be written by an individual such as a boss, or a coworker.

a personal business letter is a letter that is written by an individual to a company or between colleagues that are working for different companies. personal business letters maintain relationships with professional contacts, and it is written for various reasons such as to commend an employee, to request for an exchange or return of a product, or to request for donation of money or service.

tsd is temerature dependent sex determination.

tsd: it is a type of environmental sex determination in which the temperature experienced during embryonic/ larval development (ambient temperature for development) determine the sex of the offspring.

crocodile displays the tsd where the ambient temperature of the developing egg determines the individual's sex. for example in the american alligator's eggs, incubation at 33 ºc produces mostly males, while incubation at 30 ºc produces mostly females. so if the american alligator's egg will get the ambient temperature (33 degree celcius)during embryonic development from egg, the offspring will be male and same for the female sex determination.

and after water is usually warmed by the sun the water temperature raises and then evaporates .