你如果不舒服，一定要马上告诉老师。

Nǐ rúguǒ bù shūfu, yídìng yào mǎshàng gàosu lǎoshī.

If you feel unwell, you must tell the teacher right away.

坐久了站起来活动一下，身体会更舒服。

Zuò jiǔ le zhàn qǐlái huódòng yíxià, shēntǐ huì gèng shūfu.

After sitting for a long time, stand up and move a bit, and your body will feel more comfortable.

天气变暖了，穿这件衣服很轻，很舒适。

Tiānqì biànnuǎn le, chuān zhè jiàn yīfu hěn qīng, hěn shūshì.

The weather has become warmer, and wearing this piece of clothing feels very light and comfortable.