This sort of language helps us in:

• Expressing agreement and disagreement;
• Inquiring about agreement or disagreement;
• Denying something;
• Accepting an offer or invitation;
• Declining an offer or invitation;
• Inquiring whether offer or invitation is accepted or declined;
• Offering to do something;
• Stating whether one knows or does not know something or someone;
• Inquiring whether one remembers or has forgotten something or someone;
• Stating whether one remembers or has forgotten something or someone;
• Inquiring whether someone remembers or has forgotten something or someone;
• Expressing whether something is considered possible or impossible;
• Inquiring whether something is considered possible or impossible;
• Expressing capability and incapability;
• Inquiring about capability or incapability;
• Expressing whether something is considered a logical conclusion (deduction);
• Inquiring whether something is considered a logical conclusion (deduction);
• Expressing how certain/uncertain one is of something;
• Inquiring how certain/uncertain others are of something;
• Expressing one is/is not obliged to do something;
• Inquiring whether one is obliged to do something;
• Expressing others are/are not obliged to do something;
• Inquiring whether others are obliged to do something;
• Giving and seeking permission to do something;
• Inquiring whether others have permission to do something; and
• Stating that permission is withheld.