Do/does is necessary to ask questions other than Wh questions (who, what where, why, when, how, etc.) or be questions (is/are, was/were).

"To be", en una pregunta, se usa cómo se usaría estar/ser en español. "To do" ("do/does") se usa con otros verbos como auxiliares para formar preguntas: ¿Eres francés? = Are you French? ¿Estas en Colombia? = Are you in Colombia? ¿Te gusta esta película? = Do you like this movie? ¿Ella habla español? = Does she speak Spanish? ¿Te acuerdas de mi hermano? = Do you remember my brother? Por supuesto, hay otros tipos de preguntas que no usan to be o do/does (sino can, would, etc.). Tenga cuidado con: ¿Cuantos años tienes? (en ingles se usa el verbo "to be" para la edad) = How old are you? Ademas, en otras frases mas complicada no se usa do

Do you live here? Do you all live here? Does he live here? Does she live here? Do they live here? I do live here? Do you think it will be hot tomorrow? Does he think it will be hot tomorrow? Does she think it will be hot tomorrow? Do you all think it will be hot tomorrow? Do they think it will be hot tomorrow? I do think it will be hot tomorrow? Is it going to be hot tomorrow? Are they going to be playing football today? Are you going to be playing football today? Is he going to be playing football today? Am I going to be playing football today?

Hola! Does es siempre para la tercera persona del singular. Por ejemplo: "does she live here?" (¿Ella vive aquí?). Por otro lado, "is" se usa para la tercera persona del singular: "it is beautiful" (es precioso), "he is tall" (él es alto). Are se utiliza con la segunda persona del singular y con todas las del plural.

Puede utilizar "do" cuando el sujeto es: First person singular = I First person plural = we Second person singular = you Second person plural = you Third person plural = they Puede utilizar "does" cuando el sujeto es: Third person singular = he, she, it En cuanto a su uso aquí es un sitio web útil: http://www.grammar.cl/Present/Do_Does.htm - - - - - - - - - - - - - - - - - - - - Puede utilizar "am" cuando el sujeto es: First person singular = I Puede utilizar "are" cuando el sujeto es: First person plural = we Second person singular = you Second person plural = you Third person plural = they Puede utilizar "is" cuando el sujeto es: Third person singular = he, she, it