The test isn't saving answers between questions. I'm pretty sure Intermediate/1 has more than one solution, because the answer I got which validated made absolutely no sense to me.

The only correct answer is

    ATO
    WEL

with 'a towel' being a Hitchhiker's Guide to the Galaxy[0] reference.

[0]: http://www.wikiwand.com/en/The_Hitchhiker%27s_Guide_to_the_G...