1.To test a shell script called myscript, the environment variable FOOBAR must be removed temporarily.

　　How can this be done?

　　A.unset -v FOOBAR

　　B.set -a FOOBAR=""

　　C.env -u FOOBAR myscript

　　D.env -i FOOBAR myscript

　　Answer: C

　　2.Which command will print the exit value of the previous command to the screen in bash?

　　A.echo $?

　　B.echo $#

　　C.echo $exit

　　D.echo $status

　　E.echo $&

　　Answer: A