3 sentences

1. 他不是在偷懒，而是在思考。

   tā bù shì zài tōu​lǎn, ér​shì zài sī​kǎo.

   He is not being lazy, but rather thinking.

   Source: Dong Chinese Dictionary

2. 他干起活来比谁都快，从不偷懒。

   tā gàn qǐ huó lái bǐ shéi dōu kuài, cóng​bù tōu​lǎn.

   He works faster than anyone and never slacks off.

   Source: Dong Chinese Dictionary

3. 他总是想方设法偷懒，不愿意多干一点活儿。

   tā zǒng​shì xiǎng​fāng​shè​fǎ tōu​lǎn, bù yuàn​yì duō gàn yī​diǎn huó​r.

   He always tries to find ways to slack off and isn't willing to do any extra work.

   Source: Dong Chinese Dictionary