John 3:4

3:4 Nicodemus said to him, “How can a man be born when he is old? He cannot enter his mother’s womb and be born a second time, can he?”

John 3:9

3:9 Nicodemus replied, “How can these things be?”

John 6:41

6:41 Then the Jews who were hostile to Jesus began complaining about him because he said, “I am the bread that came down from heaven,”

John 6:52

6:52 Then the Jews who were hostile to Jesus began to argue with one another, “How can this man give us his flesh to eat?”

John 6:60

6:60 Then many of his disciples, when they heard these things, said, “This is a difficult saying! Who can understand it?”

John 12:34

12:34 Then the crowd responded, “We have heard from the law that the Christ will remain forever. How can you say, ‘The Son of Man must be lifted up’? Who is this Son of Man?”

John 16:17-18

16:17 Then some of his disciples said to one another, “What is the meaning of what he is saying, ‘In a little while you will not see me; again after a little while, you will see me,’ and, ‘because I am going to the Father’?” 16:18 So they kept on repeating, “What is the meaning of what he says, ‘In a little while’? We do not understand what he is talking about.”