单选题
In 18th-century colonial America, those who wanted to become physicians either learned as personal students from established professionals or went abroad to study in the traditional schools of London, Parisand Edinburgh. Medicine was first taught formally by specialists at the University of Pennsylvania, beginning in 1765, and in 1767 at King's College (now Columbia University), the first institution in the colonies to give the degree of doctor of medicine.
Following the American Revolution, the Columbia medical faculty (formerly of King's College) was combined with the College of Physicians and Surgeons, chartered in 1809, which survives as a division of Columbia University.
In 1893 the Johns Hopkins Medical School required all applicants to have a college degree and was the first to afford its students the opportunity to further their training in an attached teaching hospital. The growth of medical schools attached with established institutions of learning went together with the development of proprietary (私营的) schools of medicine run for personal profit, most of which had 10W standards and poor facilities. In 1910 Abraham Flexner, the American education reformer, wrote Medical Education in the United States and Canada, exposing the poor conditions of most proprietary schools. Subsequently, the American Medical Association (AMA) and the Association of American Medical Colleges (AAMC) laid down standards for course content, qualifications of teachers, laboratory facilities, connection with teaching hospitals and licensing of medical practitioners (开业医师) that survive to this day.
By the late 1980s the US and Canada had 142 4-year medical colleges recognized by the Liaison (联络) Committee on Medical Education to offer the M. D. degree; during the 1987-88 academic year, 47,262 men and 25,686 women entered these colleges and an estimated 11,752 men and 5,958 women were graduated. Graduates, after a year of internship (实习期) , receive licenses to practice if they pass an examination given either by a state board or by the National Board of Medical Examiners.

单选题 In 18th-century America, higher institutions of learning that taught medicine______.

单选题 Initially most proprietary schools of medicine in America______.

单选题 The AMA and AAMC established standards so as to______.

单选题 After a year of internship medical graduates can start to practice______.

单选题 This passage is mainly about______.