expect script , command not found

[gongotar]

hi,
i wrote an expect script that get commands from args, and executes these commands as root, i needed this script to execute commands that have space between them (i.e apt-get install git), when i give these commands that have space, the script will have my command in separated args( thats because it splits my entries by space and gives the results to each of the args), so i decided to replace all of spaces in my command with "_" and send it to my script,and then in my script replace all of "_" with " ",then try to execute it, but when i do it i get "command not found",
but when i alter my script so that it executes "apt-get install git" without getting it from args, it will execute my command correctly,what should i do?
here is my script:

#!/usr/bin/expect
set pass [lindex $argv 0]
set c [lindex $argv 1]
set command [string map {_ { }} $c]
spawn sudo $command
expect "assword"
send "$pass\r"
expect eof

[gongotar]

heyy!!any body there?!!!
my problem is that when i execute MyScript with the command : ./MyScript mypassword apt-get_install_git
i get this error:
"spawn sudo apt-get install git
[sudo] password for gongotar:
sudo: apt-get install git: command not found"

and here is MyScript:

#!/usr/bin/expect
set pass [lindex $argv 0]
set c [lindex $argv 1]
set command [string map {_ { }} $c]
spawn sudo $command
expect "assword"
send "$pass\r"
expect eof

but when i execute MySecondScript with the command : ./MySecondScript mypassword
it will execute correctly with no errors,
and here is MySecondScript:

#!/usr/bin/expect
set pass [lindex $argv 0]
spawn sudo apt-get install git
expect "assword"
send "$pass\r"
expect eof

can anybody help me?!