1. Write down two your friends' names in the blanks.
2. Write down two names of your friends' in the blanks.
3. Write down your friends' two names in the blanks.
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Which expression is grammatical?
None of them are grammatical.
In the blanks, write the names of two of your friends.
The grammatically correct expression is "Write down the names of two of your friends in the blanks."
Explanation: When providing instructions to write down names, it is more common to use the definite article "the" before "names" to indicate a specific set of names. Additionally, the preposition "of" is used to show possession, indicating that the names belong to your friends. Finally, by placing "two" before "friends," it clarifies that you are referring to two specific friends' names.