This possessive should be spelled out. You could write 'The dr.'s car would not start.' But better form dictates 'The doctor's car would not start.'
The abbreviation becomes plural - Drs. Smith and Jones.
To address multiple doctors, simply pluralize the abbreviation for doctor. For example, you would write "Dear Drs. John, Bob, and Sara".
The correct abbreviation is Dr.
Do you mean something like "Drs. John and Martha Smith"?
The proper abbreviation for extension is "ext."
The proper abbreviation for kilohertz is kHz.
The proper abbreviation for Sunday is Sun.
Drs. John and Mary Smith or if different last names Drs. John Smith and Mary Jones
IF the doctors both have the same last name you, use Drs. Smith or Drs. Jones.Addressing two or more doctors with different last names, use Dr. A. Smith and Dr B. Jones.
The proper abbreviation for Registered Chemist is RCh.
The proper abbreviation title for an attorney is "Esq."
There is no proper abbreviation for the word global. It is often symbolized by a letter G in acronyms. As far as an abbreviation goes, many people use Gl., but this is in no way a proper abbreviation.