What does this phrase mean: 'mind you'?

[english_fan]

Test No. incompl/inter-30 "Flying on a Plane", question 10

Mind you, once you've landed and you're saying goodbye to the smiling hostess, it's great to know you've ..........

(a) survived
(b) surmounted
(c) surveyed
(d) surmised

Test No. incompl/inter-30 "Flying on a Plane", answer 10

Mind you, once you've landed and you're saying goodbye to the smiling hostess, it's great to know you've survived.

Correct answer: (a) survived
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What does mind you mean? Thank you

[Alan]

This means something like of course/it is true to say/.
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English as a Second Language
You can read my ESL story A day in the life of a stately home owner

[Englishfan]

Ah, I only knew that mind means be careful.