passing variable to expect

Please tell me how to pass variable "a b c" to expect from the shell script

1/ example of input file
# cat in-file
var1 var2 a b c var4

2/ # this is my script - how to pass "a b c" as single variable ?
cat in-file | while read x
do
my-expect x
done

3/ # expect script - how to get "a b c" as single variable to expect

set var3 [lindex $argv 2]
..
send "$var3\r"

Thanks
Tam

---------- Post updated at 11:39 AM ---------- Previous update was at 11:10 AM ----------

I can put " " around a b c in my in-file - this is the description file

var1 var2 "a b c" var4