A sub-standard service or product is unacceptable because it is below a required standard.
例句
Residents in general are poor and undereducated, and live in sub-standard housing.居民们普遍都很贫穷,受教育程度低,居住条件较差。
英汉词典释义
adj.
不够标准的,在标准以下的
a substandard piece of merchandise一件不合标准的商品Too many families are still living in substandard housing.仍有太多家庭居住条件达不到标准。The reputation of the firm was blown upon for passing substandard products off as first-class merchandise.该公司因把次品当正品出售而名誉扫地。