We currently detect 4 acts of a sentence, as defined in the section 8.7 of Natural Language Understanding, 1995, James Allen. Those 4 categories are defined as surface speech acts, which indicate how the proposition described is intended to be used to update the discourse situation.
||The man ate a peach.||The proposition is being asserted|
||Eat a peach.||The proposition describes an action to perform|
||What did the man eat?||The proposition describes an object to be identified|
||Did the man eat a peach?||The proposition is being queried|