Incorrect because it would be “nosotros no llevamos” but it says YO. in order to correct it you’d need to chance the YO to NOSOTROS or change the verb to llevo.
1a. incorrect
1b. incorrect
2. before
3. No, you only need a personal a when the object is a person.
Hope this helps love!
<span>Yo entro en la cabina telefónica para usar el teléfono.
Hope it helped!
</span><span>Espero que haya sido de ayuda!</span>