"If I ever figure out an angle that I think would be useful to convey, I'll write it up" vs "If I ever figure out an angle I think that would be useful to convey, I'll write it up"? which is correct? Or are both incorrect? Why?
Another example: "I'm going to cite a comment [that] I think is in the same class" vs "I'm going to cite a comment I think [that] is in the same class". Which is correct or are both incorrect? Why?