Réponse :
a. If I left Mexico, I would go to the USA it.
b. If I found a better job in my homeland, I would not leave your country living in Mexico, you would miss.
c. If you stopped from the high crime rate, they would not flee.
d. If Mexicans did not suffer to the USA.
If Mexicans entered the USA without authorization, they would become illegal immigrants.
Explications :
If + sujet + verbe au preterit ... , sujet + would + verbe à l'infinitif sans to ...