2 sentences for 卖 (mài — spare no effort)

1. 他工作特别卖力气。

   tā gōng​zuò tè​bié mài lì​qi.

   He works exceptionally hard.

   Source: Dong Chinese Dictionary

2. 为了通过考试，他工作起来特别卖力气。

   wèi​le tōng​guò kǎo​shì, tā gōng​zuò qi​lai tè​bié mài lì​qi.

   To pass the exam, he worked extra hard.

   Source: Dong Chinese Dictionary