Esperoque hayas practicado muchos los mandados informales afirmativos (主持人:afrimativas).  Porque hoy tienes que aprender los mandados informales negativos y son muy diferentes que los mandados informales afirmativos (主持人: afrimativas).

I think other than food, and just talking to different people from around the world, what′s my favorite thing to do when I travel is to go hiking and camping.  I love being outside, and some of the world′s most amazing places are nature wonders.  Now, I like museum and historical sites, but there′s just nothing like hiking the Inca trail to Muchu Picchu, or rowing a boat on a glacier lake, or walking to a rainforest to listen to the sounds of monkeys, birds and all kinds of insects you′ve never even seen before.

I usually go with a guide or a friend who has been before, so I′m going to need so little facts of the places that we′re visiting.  Plus, it′s nice to have somebody to talk to, and share the experiences with.  And just like any museum or historical sites, there are rules to be followed. Mostly, rules that begin with NO.

No fumes.                     Don′t smoke
No pises las plantas.          Don′t step on the plants.
No nades en la catarata.         Don′t swim in the waterfall.

Rules, rules, rules!  And like I said before, I like to explore the outdoor wonders with someone who is friendly.  So, would they use the tú form or usted form to talk to me?  They′re tú form!        

And we′re friends, right?  So let′s talk about the command you would use to tell to a friend what to do, like me.  You already know the affirmative tú command is just the 3rd person singular of simple present.  But the negtive tú command is very different.  It′s used what is called, subjunctive mood.  If you know anything about Spanish, I am sure you heard of some horror stories about having to learn the subjunctive tense.  Well, they′re all lies! 

The subjunctive is so easy that you′re going to learn it today.  At least, part of it, the tú form.  You know I like to let you figure things out on your own before I just giving the answer.  So, why don′t I give you some NO rules, and see if you can figure the rule for the dreaded subjunctive in the tú form.  I′ll give you infinitive and conjugated form, so see if you can spot the difference.

affirmative tú commands use the 3rd person singular of the present indicative.

negative tú commands use the 2nd person singular of the present subjunctive mood.

caminar ---   No camines en el barro.        Don′t walk in the mud.
comer ---     No comas de esa parilla sucia.    Don′t eat from that dirty grill.
subir ---       No subas las piedras.       Don′t climb the rocks.
salir ---        No salgas del sendero.        Don′t leave the trail.

¿Lo viste?  Let′s look at the frist 3, just infinitive and negative comands.


What do you notice?  The ends are switched.  ¡Que extaño!  ¿No?

AR verbs in the subjunctive use E where you would normally have A.  And, ER verbs and IR verbs use A instead of E.

But there is one more thing, too.  How did you find the stem?  Usually you will say, drop the infinitive ending, right?

Well, that′s only for the tenes in the indicative mood, which is every tenses you have learned so far, the present, the past, the imperfect and so on.  But for the subjunctive, instead of using the infinitive, you use the 1st person singular of the present indicative minus the O ending.

stem: subjective stem is the 1st person singular of the present indicative minus the -o

For most verbs, this will be the same as infinitive stems, like caminar, the indicative stem is camin-, after you take the AR from the infinitive.  And camin-, after you take the O from camino.


But there are many others, including all the spelling changers, stem changers and irregulars.  That will be very different.  Take that last example I gave you.

Salir ---   No salgas del sendero.


Once you find your subjunctive stem,  you just add those opposite ending you just learned seconds ago.

For AR verbs, for a (negative) TÚ command, you′ll add ES.
And for ER and IR verbs, you′ll add AS.        

Wanna try a few?  I′ll set you up with some negative TÚ commands and help you along.  I′ll give you both infinitive and yo form of indicative present.  ¿Listo?  ¡Hagamos juntos!        
       
(Olvidar / Olvido) usar el repelente antiinsectos y el bloque del sol.        
    No olvides       


(Permitir / Permito)______ a los mosquitoes ni las moscas entrar en la tienda de acampar.        Don′t let those mosquitos nor the flies in the tent.
                         No permitas        
        
(Usar / Uso) ____ los fósforos para la leña mojada.   
Don′t use the matches on the wet wood.
                 No uses         
        
(Pisar / Piso) ________ las hormigas.     Don′t step on the antes.
                    No pises        
        
(Mirar / Miro) _____ el sol con los binoculares.  
Don′t look at the sun with the binoculars.
                   No mires         
        
(Molestar / Molesto)  _____ las ardillas.   Don′t bother the squirrels.
                           No molestes


Vocabulary for Learn Spanish 2.13 - Negative Informal Commands in the Wilderness

el repelente antiinsectos    nm.  insect repellent.
el mosquito
pisar                    vt.    to step on
el riachuelo          nm.  stream, brook
la parilla              nf. grill  烤架,(烤爐等上的)烤盤;烤肉,烤魚
los binoculares     nmpl.  binoculars
la linterna         nf.  flashlight
la leña            nf.  firewood
el barro          nm.  mud
el fósforo       nm.  match
la mosca        nf. fly
la hormiga     nf  ant
la planta       nf.  plant
el sendero     nm  trail
la catarata     nf  waterfall
la piedra        nf  stone, rock
la ardilla         nf squirrel
el sol                 nm   sun
la tienda de acampar    nf.  tent
el bloque del sol     nm.  sunblock