4 sentences

1. 市面上有很多劣质商品。

   shì​miàn shàng yǒu hěn​duō liè​zhì shāng​pǐn.

   There are many low-quality products on the market.

   Source: Dong Chinese Dictionary

2. 这件毛衣的款式挺特的，市面上很少见。

   zhèi jiàn máo​yī de kuǎn​shì tǐng tè de, shì​miàn shàng hěn shǎo​jiàn.

   The style of this sweater is quite unique and is rarely seen on the market.

   Source: Dong Chinese Dictionary

3. 这种款式的青花瓷器在市面上非常少见。

   zhè zhǒng kuǎn​shi de qīng​huā​cí​qì zài shì​miàn shàng fēi​cháng shǎo​jiàn.

   This style of blue and white porcelain is very rare on the market.

   Source: Dong Chinese Dictionary

4. 市面上有很多专为左撇子设计的吉他，方便他们练习弹奏。

   shì​miàn shàng yǒu hěn​duō zhuān wèi zuǒ​piě​zi shè​jì de jí​tā, fāng​biàn tā​men liàn​xí tán​zòu.

   There are many guitars on the market designed specifically for left-handed people, making it convenient for them to practice.

   Source: Dong Chinese Dictionary