千万 + 别/要 + Verb
千万 is an adverb used to add strong emphasis to a reminder or warning, meaning "be sure to" or "whatever you do." It is often used with 别 or 不要 to form urgent negative commands. For example, 千万别忘了 means "whatever you do, don't forget."
明天面试,千万别迟到。
Míngtiān miànshì, qiānwàn bié chídào.
You have an interview tomorrow — whatever you do, don't be late.
这件事千万不要告诉别人。
Zhè jiàn shì qiānwàn bùyào gàosù biérén.
Whatever you do, don't tell anyone about this.
出门千万记得带钥匙。
Chūmén qiānwàn jìde dài yàoshi.
When you go out, make sure you remember to bring your keys.