1 sentence

1. 他在学习珠算时，正在努力背诵九归口诀。

   tā zài xué​xí zhū​suàn shí, zhèng​zài nǔ​lì bèi​sòng jiǔ​guī kǒu​jué.

   While learning abacus calculation, he was working hard to memorize the division formulas.

   Source: Dong Chinese Dictionary