My grandfather lived only half a mile away from where I grew up in New York. Every day, he would walk down to our house and bring my dad newspapers. Along with the papers he would bring a small bag of treats for my two brothers and me.
Western NY had terrible winter weather: rain, sleet, or even 3 feet of snow. Even when he was 81, he still walked the half mile every single day. As a child, I looked forward to the daily treats, but now I’m older and I realize he braved the rough weather each day just to see us smile; I now value that more than anything else.
My grandfather touched many lives. A woman who had been in hospital for five years told me her story. She said my grandfather would visit her twice a week at her home: to read to her, play bridge, or just chat. It lasted for years without stop. She had few visitors. Even a hitchhiker who my grandfather had picked up for free told me of my grandfather’s influence on his life. My grandfather took the traveler to his home. After learning that the man was homeless, my grandfather gave him a place to stay. The man told me that no one had ever been so nice to him. He later found a job in a supermarket.
I was touched, but not surprised to know all of the touching stories from which I understood my grandfather’s selflessness. I have since tried to learn from him to help others. Although he died years ago, we still respect him.

The underlined word "hitchhiker" in Paragraph 3 refers to ______.

A．a person who gets a free car ride when traveling
B．a person who likes traveling by car
C．a person who is given up by parents
D．a person who travels alone and gets lost

下列哪项不是唾液的生理作用

A．部分消化淀粉和麦芽糖

B．清洁和保护口腔

C．湿润和溶解食物

D．分解食物中的脂肪