A.Only animal tears are to be valued.
B.Only animal tears can kill certain bacteria.
C.Only humans cry for others.
D.Only humans cry in response to emotions.
A.Boys cry four times as often as girls.
B.Girls cry four times as often as boys.
C.Boys cry as often as girls.
D.Girls cry a quarter as often as boys.
A.Why humans cry.
B.How to relieve ourselves.
C.How animals cry.
D.When people cry.