虽然它小，但是很漂亮。 Suīrán tā xiǎo, dànshì hěn piàoliang. Although it is small, it is very beautiful.
虽然我很累，但是我还想看书。 Suīrán wǒ hěn lèi, dànshì wǒ hái xiǎng kàn shū. Although I am tired, I still want to read.
虽然我累，但是我学习。 Suīrán wǒ lèi, dànshì wǒ xuéxí. Although I am tired, I still study.
虽然他很大，但是他很可爱。 Suīrán tā hěn dà, dànshì tā hěn kě'ài. Although he is big, he is very cute.
虽然……但是…… is pronounced suīrán…dànshì… and means “although… but…”. It is one of the words in the HSK 2 vocabulary, a level of the Hanyu Shuiping Kaoshi, China’s standardised Chinese proficiency test. Recognising a word on a page and recalling it when you need it are different skills, and only the second survives a conversation — which is why LexiTrail shows you 虽然……但是…… again just before you would have forgotten it, rather than on a fixed schedule.