in/out to Fragment Shader from Geometry Shader using GLES31 (#version 310 es)

Question

in/out to Fragment Shader from Geometry Shader using GLES31 (#version 310 es)

block interface is not supported, VS and FS in GLES31

And simply in/out like below

GS

out lowp float tmp;
void main()
{
tmp = sumValue;
}

FS

in lowp float tmp;
void main()
{
oColor = tmp * usingTmp;
}

Then, program is running, but color blink.

how to use in/out between GS and FS ?