By this method, by not using PC only using s939,
in addition, you can use Kingo Root without using dangerous kingroot.
1. Please install and get root permission by "Kingo Root.apk".
This process advances, and you will fail at 90%-progress.
However, you should continue it.
2. Please install "kingo superuser" using google play store.
You will get temporary root permission in this, even if you failed at the stage before.
3. Please install "RecoveryInstaller.apk".
You can fetch this from "4shared.com" as "RecoveryInstaller_S939_1.1.apk."
This application is written in Russian, but you can understand how to use.
4. Please pick up rooted ROM for s939.
You can pick it up if you search it by using key-words "s939" and "rom".
(This site is "needrom.com".)
You can choose favorite ROM if you register e-mail address.
I chose "MIUI7 5.9.26 multi", and I like it very much.
5. Please install the application which can "reboot recovery"
using google play store.
6. After "reboot recovery",you can use CWM Recovery,
you have to wipe cashe and data properly, and please flash rooted ROM .
My s939 was the slightly doubtful thing which installed kitkat,
and became Chinese factory mode by button operation,
but got complete root permission by this method.