谈一谈 （V一V） “Talk about” 

    Monosyllabic verbs can be used with 一inserted in between. Reduplicated verbs, in general, have a less formal effect than those with them. They have two basic forms: monosyllabic reduplication and disyllabic reduplication. 一and the repeated monosyllable verb usually take neutral tones. This form has basically two functions: 

(1) To indicate an action of short duration.
Examples:
1. 我得想一想。
I have to think about it.

2) To soften the tone and to make the speaker's tone less formal. This function is usually used in requests and suggestions.
Examples:
2. 这个工厂值得看一看。
This factory is worth visiting,
 
                   Subj. +V一V +(Obj.)
Substitutive drills: