If you have the sound shi but not the character, here are the 6 characters read this way: 十 (shí, ten; complete; cross), 时 (shí, time, hour, season), 实 (shí, real, solid, true, actual), 事 (shì, matter, affair, thing-that-happens), 是 (shì, to be). They split across 2 tones, so the tone is what separates them.