In referring to an action taking place regularly (and not limited to the future or to the past), the simple present is used: "He brushes his teeth every morning". For an action taking place at the present time, the present progressive construction is used: "He is brushing his teeth now". With some verbs expressing a present state, particularly the copula "be" and verbs expressing a mental state, the present simple is generally used: "They are here"; "I know that". However other state verbs use the present progressive or present simple depending on whether the state is considered temporary or permanent: "The pen is lying on the table"; "Paris lies on the Seine".