A sequence structure

and IF, THEN whilst a dual alternative selection contains IF, THEN, ELSE

I guess the alternative would be to have several single-purpose projects.

Single Alternative Selection Structure is a binary (IF>THEN) statement. IF condition X is met THEN do this.

Dual Alternative Selection Structure is when more than one option exists and the statement has the possibility to take the program in different directions, based on the response. IF condition X is met THEN do this, ELSE do something differently.

There is not a single word that is an alternative word to never. However, there are combinations of words which mean basically the same thing. Some include not ever or at no time.