***if you have had experiences with crushes, answer

background info- a guy at school has a crush on me, since mid-october. he is very talkative and hyper around other people, but around me, he is verrryyy quiet. if i ask him a question he would only answer with between 1-3 words, while with other people he would just talk normally. i noticed when the first time i approached him, he just constantly stared into my eyes and smiled, showing his teeth. the second time i approached him, he didn't stare at me at all.. his eyes were focused on the floor and he didn't smile. this time he looked really nervous!
okay here is the point of the
so it was just a normal day at lunch. i sat at my normal seat with a group of friends. (which, by the way, most were guys) about halfway through the lunch break, i sensed that something was up. in the corner of my eye, i see him walking towards me with his hands behind his back. so i'm like "oh gosh, here it comes".
here is how the conversation went-
guy - *approaches me looking nervous*
guy - "hi! " *with a nervous smile, showing teeth*
me - "hey! " *caught off guard, also smiling*
guy - "i got these for you"*gives me stuff from the bake sale*
me - "oh my gosh you so much! "
my guy friend beside me - "you should go sit by him"
me - "a umm i don't know if i'm ready yet"
guy - *still standing there, smiling awkwardly*
me - "anyways so much."
guy - *turns and walks away*
(^this situation happened around the beginning of december^) so what i'm wondering, why the heck did he give me a he is so shy around me and all a sudden he just gives me hasn't had a crush on me for that do you think you'd know

***if you are going to answer then be thorough with it, i'm not going to give away free points ! ***

The primary function of the respiratory system is to supply the blood with oxygen in order for the blood to deliver oxygen to all parts of the body. the respiratory system does this through breathing. when we breathe, we inhale oxygen and exhale carbon dioxide. this exchange of gases is the respiratory system's means of getting oxygen to the blood. respiration is achieved through the mouth, nose, trachea, lungs, and diaphragm. oxygen enters the respiratory system through the mouth and the nose. the oxygen then passes through the larynx (where speech sounds are produced) and the trachea which is a tube that enters the chest cavity. in the chest cavity, the trachea splits into two smaller tubes called the bronchi. each bronchus then divides again forming the bronchial tubes. the bronchial tubes lead directly into the lungs where they divide into many smaller tubes which connect to tiny sacs called alveoli. the average adult's lungs contain about 600 million of these spongy, air-filled sacs that are surrounded by capillaries. the inhaled oxygen passes into the alveoli and then diffuses through the capillaries into the arterial blood. meanwhile, the waste-rich blood from the veins releases its carbon dioxide into the alveoli. the carbon dioxide follows the same path out of the lungs when you exhale. the diaphragm's job is to pump the carbon dioxide out of the lungs and pull the oxygen into the lungs. the diaphragm is a sheet of muscles that lies across the bottom of the chest cavity. as the diaphragm contracts and relaxes, breathing takes place. when the diaphragm contracts, oxygen is pulled into the lungs. when the diaphragm relaxes, carbon dioxide is pumped out of the lungs. write one paragraph (at least 6 sentences) describing the path of oxygen through the respiratory system. also include why this "order of operations" is the way it is!