2 sentences

1. 他一坐下，就拿起了电话。

   tā yī zuò xia, jiù ná qǐ le diàn​huà.

   As soon as he sat down, he picked up the telephone.

   Source: Tatoeba

2. 我一坐下就睡著了。

   wǒ yī zuò xia jiù shuì zhe le.

   As soon as I sat down, I fell asleep.

   Source: Tatoeba