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 4:11

4:11 “Sir,” the woman said to him, “you have no bucket and the well is deep; where then do you get this living water?

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 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.”