Anchor: In fact, some impotence researchers assert that the success rates of prostaglandin may not be much better than the success rates of placebos.
Entailed: Placebos may be working just as well as prostaglandin. 
Contradiction: Placebos have a much lower success rate than does prostaglandin.
Contradiction: Two workers are digging a very large hole.
Contradiction: There were huge halls and lots of statues.
Contradiction: A cat is eating a mouse.
Contradiction: An old man trying to get to a crate