11. What substance can be stimulated to be secreted in the human body when kissing passionately?
a) Adrenaline
b) Insulin
c) Estrogen
d) Dopamine
12. What role might human dead skin play in the air?
a) Polluting the air
b) Purifying the air
c) No effect
d) Accelerating oxidation
13. What percentage of force can the little finger provide in physics?
a) 20%
b) 30%
c) 40%
d) 50%
14. How much sweat can the sweat glands on a person’s foot secrete on average per day?
a) 0.5 liters
b) 1.1 liters
c) 2.0 liters
d) 3.5 liters
15. What is the total number of cells in a human body?
a) 1 trillion
b) 10 trillion
c) 100 trillion
d) 1 quadrillion