Spanish pronunciation

It is said that Spain and Portugal hvae the lowest number of English speakers in Europe. Speaking Spanish is essential to survive here.
The Spanish who do speak English often have problems with pronunciation. Many cannot make the ´sh´sound or the ´j´sound. The ´zh´sound is also another one. These sounds don´t exist in Spanish.
Whatsmore, some students have problems sounding some vowels. I recently had a student who couldn´t say the word ´sheet´without saying ´shit.´ After 15 minutes of trying to get him to make the ee sound, the guy just simply went back to saying ´shit.´