How do I use the subjunctive after negative statements?

Grammar Genius,

I am a little confused about how to use the subjunctive after negative statements such as "nadie, nunca, etc." Why do I use the subjunctive in "Nunca haré lo que me mandaran si no me dan alguan razón para ello,¨ (I will never do what they ordered me to do if they do not give me a reason for it) if doubt is not involved in the sentence?

When the subordinate clause contains an indefinate or negative subordinating conjunctions, such as seen below, the subjunctive is used. Keep in mind that the below list is not inclusive and that the basic formula is: negative statement + que + subjunctive.

nadie que	no one that
ninguno (a) que	nothing
ninguna cosa que	nothing that
alguien que	someone that
alguno que	something that
uno (a) que	one that
cualquiera que	anyone who
comoquiera que	however
dondequiera que	wherever that
quienquiera que	whoever
cada vez	whenever

NOTE: If any of the above antecedents are used to express a conclusive action (in the past or present) or a definate idea, the subjunctive is not needed. Compare the following:

Vamos a comprar una casa que tenga una vista, que sea de madera, y que esté en el campo, que no sea cara.	We are going to buy a house that has a view, is made of wood and is in the countryside, that isnīt very expensive
Compramos una casa que tiene una vista, es de madera, y esta en el campo.	We bought a house that has a view, is made of wood and is in the countryside. (conclusive action)

Given each of the questions below, type in the correct response.  Although capitalization does not count, spelling does!

Please enter your name

1. No hay ningún medicamento que (curar) de la misma forma, a todos los enfermos.

2. No he conocido a nadie que (resistir) la lectura de ese libro.

3. Nadie que se (estimar) medianamente, podría admitir una cosa así.

4. Yo creo que hoy día no quedan personas que (pensar) así.

See also, using the subjunctive to refer to the unspecific.