試題詳解

47 What is the main idea of the second paragraph?
(A) The meaning of the word endorphin shows its ability to take away our pain.
(B) When we have sex, do exercise, or eat food, our brain calls for endorphins.
(C) The word endorphin is formed by the two words endogenous and morphine.
(D) Endorphins stop sending pain signals by locking into special receptor cells.