十分感谢你这段时间的帮助。

Shífēn gǎnxiè nǐ zhè duàn shíjiān de bāngzhù.

Thank you very much for your help during this time.

她写了一封信感谢老师多年的教导。

Tā xiě le yī fēng xìn gǎnxiè lǎoshī duōnián de jiàodǎo.

She wrote a letter to thank her teacher for years of guidance.

谢谢你帮我照顾孩子，我真的很感谢。

Xièxie nǐ bāng wǒ zhàogù háizi, wǒ zhēn de hěn gǎnxiè.

Thank you for helping me take care of the children; I'm truly grateful.