Solution to 10.

10. Unless something has changed, even if you turn that key the car won't start.

Doing the obvious grouping, we get:

Unless (something has changed), even if (you turn that key) (the car won't start).

The 'unless' is a disjunction, and the two disjuncts are clearly separated by the comma:

(something has changed) OR {even if (you turn that key) (the car won't start)}

The second disjunct has the form: 'even if ..., ...'. How do we translate this? It is clearly a conditional. The material immediately following the 'if' is the antecedent, and so the other statement must be the consequent.

(something has changed) OR {if (you turn that key) then (the car won't start)}

The simple statements are

S = Something has changed.

K = You turn that key.

C = The car will start.

Substituting we get: