PRESENT CONTINUOUS.

Affirmative.
 
*I +am = ´m
*He/She/It +is = ´s                  +ing.
*You/We/They +are = ´re
ej: I am studying French. Estoy estudiando francés.
 
Negative.
 
*I +am not = ´m not
*He/She/It +is not =isn´t                +ing.
*You/We/They +are not =aren´t
ej: I am notstudying German. No estoy estudiando alemán.
 
Interrogative.
 
*Am + I
*Is +he/she/it            +ing.
*Are +you/we/they
ej: Are you studying history? ¿Estás estudiando historia?