The patient's voice was a little horse, and he complained of sore throat, so the doctor prescribed a throat lozenge.

horse/prescribed/lozenge/so
which word would be correct here? so is wrong,thanks.

Have you looked up these words in a dictionary?

What do you think?

i check that already,prescribed should be prescribe

No. Prescribed (past tense) is correct.

What definitions did you find for horse and lozenge?

a rhombus or diamond shape.lozeng

horse=a frame or structure on which something is mounted or supported, especially a sawhorse.
still confusing

The voice was a little frame or structure?

so horse

thanks for help

In this sense, it's spelled hoarse.

https://www.google.com/#q=hoarse

You're welcome.

http://www.google.com/#q=hoarse

Based on the context you provided, the correct word here would be "hoarse," not "horse." The sentence would then read as: "The patient's voice was a little hoarse, and he complained of a sore throat, so the doctor prescribed a throat lozenge." "Hoarse" describes the quality of the patient's voice being rough or raspy.