A、Basal tears. B、Reflex tears. C、Emotional tears. D、Physical tears. D

As humans we laugh and cry, but seldom do we question how, or why.
   Crying is a more complicated process than one would at first imagine. First of all, there are really three different types of tears. Basal tears keep our eyes lubricated constantly. Reflex tears are produced when our eyes get irritated, like with onions or when something gets into our eyes. The third kind of tear is produced when the body reacts emotionally to something. Each type of tear contains different amounts of chemical proteins and hormones. Scientists have discovered that the emotional tears contain higher levels of manganese and the hormone prolactin, and this contributes to a reduction of both of these in the body: thus helping to keep depression away. Many people have found that crying actually calms them after being upset and this is in part due to the chemicals and hormones that are released in the tears.
   How then actually do we cry? The psychic tears require an emotional response, or trigger to be activated. This response can be caused by an outside source, either pain or loss of love, etc., or from an inside source. When emotions affect us, the nervous system stimulates the cranial nerve in the brain and this sends signals to the neurotransmitters to the tear glands. Thus, we cry. The largest tear gland, the lacrimal gland produces the tears of emotion and reflex. Many believe that the body, in times of emotional stress, depends on this gland to release excess amounts of chemicals and hormones, returning it to a stable state.
15. Which type of tears is not mentioned in the talk?
16. Which of the following statements is not true?
17. How do we actually cry?
18. What is the largest tear gland inside our body?