 
 <prompt> Wen pesin fit sabi say one dialect of language dey hard na wen e dey try learn am and e dey see say e dey confuse am well well. E fit dey hard for pesin to understand di grammar, vocabulary, and pronunciation of di dialect. Some people fit find am difficult to learn new dialects wey get different tones or sounds wey dem no dey use for dia own language. For example, if pesin wey dey speak English try learn Chinese wey get tonal sounds, e fit dey hard for am to sabi pronounce di words correctly. So, na so pesin fit know say one dialect dey hard for am to learn based on how e dey struggle to understand and speak am. <response>: ```The most common, and most purely linguistic, criterion na say if two varieties fit understand each other well well, then dem be dialects of the same language; if dem no fit understand each other, then dem be different languages. But sometimes e fit dey hard to decide if dem be dialects or not, especially if dialect B fit understand both dialect A and dialect C but dialects A and C no fit understand each other. Sometimes too, e fit happen say person wey dey speak dialect X fit understand person wey dey speak dialect Y, but the person wey dey speak dialect Y no fit understand person wey dey speak dialect X; for dis kind situation, the mutual intelligibility criterion dey fail.``` 