What is the difference between "Write it down" and "Write down it"?

Question

Oh hi! thanks for reading this question.

I'm an English learner and I just want to know what's the difference between "Write it down" and "Write down it"?.

Can you elaborate?

Thanks!

Answer 1

The difference is that the latter is ungrammatical. In a prepositional verb, an unstressed pronoun such as "it" must directly follow the verb. This is explained in Huddleston & Pullum (2005: 144):

One general constraint on the order 'particle + object' is that it is inadmissible if the object has the form of an unstressed personal pronoun (italic mine). For example, we can replace the suitcase by unstressed it in [36ia] but not in [iia]:

a. She took it off
b. * She took off it

Answer 2

Some verbs in English are phrasal verbs, these are formed of a verb and a particle. Usually, the particle can also function as a preposition. Examples of phrasal verbs are "Turn on" and "get off"

Phrasal verbs can be "separable" or "inseparable". When a phrasal verb is separable, and the object of the verb is a pronoun, the pronoun is moved between the verb and preposition. "Turn on" is separable, but "look after" is inseparable.

Examples:

Turn on the light
Turn it on
Look after the child
Look after her

"Write down" is a separable phrasal verb, so you say

Write down the sentence.
Write it down.

There is no rule for telling if a verb is separable or inseparable. In inseparable verbs the meaning of the preposition is often closer to its usual meaning but this only a rough guide, and doesn't explain every verb.

Answer 3

I think 'write down it' is wrong; we should say ‘write it down’. You can say ‘write the article down’ or ‘write down the article’. When a phrasal verb follows the pronoun, it should not be separable but if it follows a noun it may or not be separable.