美国为什么又叫USS

有很多种解释. USS may refer to:

Various organizations:

Union of Secondary Students, a student-rights advocacy group in Ireland
Union Switch & Signal, a supplier of railroad switching equipment
Union Syndicale Suisse, the Swiss Trade Union Confederation
United Seamen's Service
United States Senate
United States Steel Corporation
USA Swimming, formerly United States Swimming, the National Governing Body for competitive swimming in the United States

In computing:

Unformatted System Services, the mechanism within VTAM to format a terminal's initial screen and route to selected applications. Sometimes also referred to as USSTAB or USS Table which is the assembler macro used to in the construction of such screens. The resulting screen image is called a USS message.
UNIX System Services, a component of z/OS
Upload Speed Sense, a method of regulating a host's upload bandwidth in the eMule cli