语法有错误否 "sth is cheap but have good quality"

确实语法错误，应该是sth is (cheap but good quality.)。次句中中"cheap"和 "quality"是同等的形容词，在句中的成分是并列的，所以不能按照惯性思维认为那是“有好质量……”的说法~

sth is cheap but has good quality
have ---has

is是第三人称单数 而have是复数或者是第二人称做主语
前后不一致

sth is cheap but has good quality

严重语法错误
a lot of sth and it very cheap

前面用的是is,后面要对应啊，应该是has。