Case 1: “Every triangle necessarily has three sides so long as it is a triangle” expresses a necessary relation tied to the nature of a triangle.
Case 2: “A person writing by hand moves their fingers while writing” is restricted by a descriptive title; if necessity during that activity is intended and supported, it has the generally conditional form.
Case 3: “The Moon is eclipsed at this stated occasion” mentions a specified time; strict time-specific necessity also needs the necessity of that relation to be stated or supported.
Case 4: “This student is standing now” reports actuality, not necessarily permanence or necessity.
For each expression, establish subject, predicate, temporal/descriptive restriction and modal force before assigning its technical class.