The arguments in this exercise are syllogisms. They contain two premises and one conclusion each of which begins with ALL, NO, or SOME and each of which relates the members of one group to the members of another.

For example:

The form or structure of an argument:

Shows the ALL-NO-SOME-NOT patterns,
Shows the location of repeated terms, and
Separates the premises from the conclusion.

In the above example, the form is:

Some H are Not S
No H are F
So, some F are S

The arguments in this exercise are FORMALLY INVALID. That is, the inference depends entirely on the form and not at all on any other factor. Thus, the English arguments can be proven invalid by

(1) finding their form.
Then (2) finding another example of the same form with true premises and a false conclusion.

The form above is proven invalid by the following