>>I ma not a native English speaker. However, I have to use English to do reading, thinking and a lot writing. After years working in the computer tech World, I still cannot tell what is the difference between the words 'System' and 'Systems' in cases such as:
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>>Operating System v Operating Systems
>>Database System v Database Systems
>>System Analist v Systems Analist
>>...
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>>I would appreciate anyone who cares to offer an English lesson.
>>
>>Chen
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>In each case, the first one is single, or one OS, DS, SA. The second one is multiple. For example, 2 or more Operating Systems (NT, Windows 95). The same for DA & SA.

Thanks Craig,

I may look stupid to ask this question. However, I learned to use a singular form of a word to be used as an adjective, for example, we say: he is a horse rider or a car repairman. On the other hand, I would say I am a systems analyst and I do systems analysis and systems design. So you native speakers feel it is ok or even preferable to use the plural form, systems, instead of a singular form, system, in these cases.