The English Present Tense
English present-tense verbs can take three forms which most English speakers do not conscientiously employ; they simply say what “sounds right" at the moment. One form called the simple present simply indicates the action is taking place now:
Sue sees the beautiful tree.
Mark listens to music.
Sally writes a story.
The present progressive uses the word “is" (or “are" in the plural) to indicate that the action is taking place now:
Sue is seeing the beautiful tree.
Mark is listening to music.
Sally is writing a story.
The present emphatic uses the word “does" (or “do" in the plural) to indicate that the action is happening now:
Sue does see the beautiful tree.
Mark does listen to music.
Sally does write a story.
This may seem insignificant to the English speaker because as stated above, most English speakers just say what sounds right. However, present tense sentences that ask questions can only use the present progressive and present emphatic tense form. For example:
Is Sue seeing the beautiful tree? (Does Sue see the beautiful tree?)
Is Mark listening to music? (Does Mark listen to music?)
Is Sally writing a story? (Does Sally write a story?)
Notice that in each of the six example questions above, the tone of the question changes from the progressive to emphatic form. Each would be used under different circumstances depending on the intention of the speaker and, yes, what “sounds right" as a result.