So can I use you guys?

I want to poll some people on the grammaticality of some sentences (because opinions differ, and because when you start working on assignment you end up a little turned around and lose your sense of what is grammatical). Two things to get out of the way:

- 'grammaticality' is just whether you would say the utterance.
- punctuation doesn't matter for the purpose of these sentences, so ignore that.

Some sample sentences for you to judge:

(3) I believe [that the idea [that pigs can fly] seems reasonable].
(4) [that a guy likes bikes] makes sense.
(5) I don't know [if billy ate the cat].

(6) The boy [who left home] came back.
(7) [That the boy [who left home]] came back] was fortunate.
(8) [That [that he went home] is a fact] won't change anything.

(the brackets just denote CPs and RCs, disregard them)

As thanks, I'll show you this pretty picture:

[img]http://oi58.tinypic.com/2n07om9.jpg[/img]