Subject + 意识到 + Clause
The word 意识 (yìshí) can function as both a noun meaning 'consciousness' or 'awareness' and a verb meaning 'to realize' or 'to become aware of.' As a verb, it is commonly followed by 到 to introduce what one has realized. For example, 意识到 means 'to realize that.'
他终于意识到自己犯了一个大错误。
Tā zhōngyú yìshí dào zìjǐ fàn le yí gè dà cuòwù.
He finally realized that he had made a big mistake.
很多人没有意识到这个问题的严重性。
Hěn duō rén méiyǒu yìshí dào zhège wèntí de yánzhòngxìng.
Many people haven't realized the seriousness of this problem.
她突然意识到时间已经很晚了。
tā tūrán yìshí dào shíjiān yǐjīng hěn wǎn le.
She suddenly realized it was already very late.