Understanding Human Eye Blinking

The passage discusses the natural process of human eye blinking. Blinking is a vital function that helps keep our eyes healthy and clean. Let's break down the blanks based on the information given.

Analyzing the First Blank: Why Humans Blink

The first blank describes the manner in which humans blink to flush away tears. The passage states that blinking is done to "flush away the stream of cleansing tears produced by the ducts present in the corners of our eyes." This action is primarily an involuntary reflex, although we can also blink voluntarily.

• The word "automatically" suggests an action that happens without conscious thought, which aligns well with the natural, reflexive nature of most blinking.
• "Deliberately" means done on purpose, which is not the usual way we blink for tear distribution.
• "Impulsively" means acting without thinking, which is close to automatic but less precise for a consistent physiological reflex.
• "Mechanically" describes something done like a machine, which captures the automatic aspect but "automatically" is a more common and appropriate term for a biological function.

Based on this, "automatically" is the most fitting word for the first blank as human blinking, for the purpose described, is largely an automatic bodily function.

Analyzing the Second Blank: How Often Adults Blink

The second blank requires a verb to describe the action adults perform approximately 15 times per minute. The passage is clearly talking about the act of closing and opening the eyes rapidly, which is called blinking.

• "Blink" is the correct and standard term for the action of closing and opening the eyes, usually both eyes simultaneously, often involuntarily.
• "Flutter" can describe rapid, light movements, but it's not the precise term for a full closure of the eyelids.
• "Wink" is typically closing only one eye, often as a signal, and is not the general term for the action happening 15 times a minute.
• "Flicker" usually refers to a quick, unsteady light or movement, not the closing of eyelids.

Therefore, "blink" is the correct verb for the second blank.

Putting It Together: The Completed Sentence

Combining the most appropriate words for each blank, the sentence becomes:

Humans blink their eyes automatically to flush away the stream of cleansing tears produced by the ducts present in the corners of our eyes. Adults blink their eyes about 15 times per minute.

This completed sentence makes sense and accurately describes the physiological process of blinking.

Revision Table: Key Blinking Terms

Additional Information: The Importance of Blinking

Blinking is far more than just an automatic reflex. It performs several critical functions for maintaining eye health:

• Lubrication: Each blink spreads a thin layer of tears across the eye's surface, keeping it moist and preventing dryness.
• Cleaning: Tears wash away dust, debris, and irritants from the eye. The eyelid acts like a windshield wiper.
• Protection: Blinking provides a quick, protective shield against foreign objects, bright lights, or sudden movements towards the face.
• Nutrient Supply: Tears contain essential nutrients and oxygen for the cornea, which doesn't have blood vessels.
• Vision Clarity: By keeping the eye surface smooth and moist, blinking helps maintain clear vision.

The rate of blinking can change depending on what a person is doing. For example, people tend to blink less often when concentrating on a computer screen or reading, which can sometimes lead to dry eye symptoms.