【正确答案】topic In the lecture, the professor says that tears help protect our eyes in two approaches, and he gives examples on the two types respectively. example 1 The first type is basal tears, which are produced usually to help preserve moisture and kill bacteria. For example, basal tears come from one's blinks would protect our eye balls from being attacked by bacteria. example 2 The other type is reflex tears, not very often produced. No sooner had particles come into our eyes than they came Out, washing away the particles harmful to our eyes. Suppose you are on a beach, the reflex tears come out to wash away the sand which is blown into your eyes.

【答案解析】[听力原文] M: The human eyes are very fragile and exposed, so they need to be protected. Do you know tears can do some amazing things to protect our eyes? Indeed, they are able to protect human eyes in two different ways. Firstly, basal tears are produced quite often, and help keep eyes moist and protect the eyes from bacteria. For example, when people blink their eyes, tears come out and produce a thin film in order to protect our eyes from the attacks of bacteria as well as stop the eyes from drying out. The second type of tears are reflex tears: these tears are produced when foreign particles or objects land in the eyes, and the tears are produced in the tear ducts to flush out or wash away the particles that may be harmful to the eyes. Have you ever had sand in your eyes? What happened? Your eyes' natural defenses create the reflex tears in order to wash the sand out before any damage is caused.