how long do you know it? vs how long did you know?

The correct phrase is "How long did you know?" This is the correct past tense form of the question. The other phrase, "How long do you know it?" is incorrect because it mixes present tense (do) with past tense (know).

Last updated: March 25, 2024 • 1062 views

how long do you know it?

This phrase is incorrect. It mixes present tense (do) with past tense (know).

This phrase should not be used as it is grammatically incorrect. When asking about the duration of knowing something in the past, the correct form is to use the past tense.

Show examples from the web [+]

Your woman, how long do you know her?
How long, do you know?
Do you know how long'?
How long do you know this already?
How long you know about this?
So how long did you know Quintana?
So how long you know Rick?
New lungs work, but for how long, you know?
How long do we know eachother?
Were they married long, do you know?
So, how long did you know Bridgett?
Tell me, how long do you know the doll?
Were they married long, do you know?
How long did she know Fletcher?
- Do you know it? - Every German knows that story.
Life is long, you know? Live it up.
Do you know how long I had it?
May I ask how long know each other?
Do you know how long that's going to take? Resource is sending a security detail to defend the hospital and give us time to evacuate.
Do you know how long they were together?

how long did you know?

This phrase is correct and is the past tense form of the question.

This phrase is used to ask about the duration of knowing something in the past. It is the appropriate way to form this question in English.

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how long do you know it? vs how long did you know?