（Ⅰ）求f（x）的最小正周期、零点；

（Ⅱ）求f（x）在区间 $\frac{\pi }{24}，\frac{3\pi }{4}$ 上的最大值和最小值．

虾青素（C₄₀H₅₂O₄）可增强动物免疫力,下列有关它的说法正确的是（）

   One evening I went to have dinner with my uncle and aunt. They had 1invited another person, a young woman, so that there would be four people at 2. Her face was familiar (面熟的). I was quite 3　that we had met 4, but I could not 5　where I had seen her face. In the course of the talk, however, the young woman6to tell us that she had lost her purse the other day. All at once I remembered where I had seen her face. She was just the young girl in the photo in the purse I had picked up while walking down the street that afternoon, although she looked much older. She was7, of course, when I was 8　to describe her purse to her. Then I explained (解释) that I had recognized (认出) her from the photo I had found in the purse. My uncle insisted on going to the police station immediately to fetch the purse.
   As the policeman handed it 9 he said I had found not10the purse, but the person who had lost it.

    Alisa was walking around the swimming pool. Her friend Maria was waiting for her. "Come on, Alisa!" Maria said. "Let's jump off the diving board (跳水版)."

    "No way! I can never go that high," said Alisa.

    "Don't be scared," Maria said. "It's really fun."

    Alisa walked away and sat on a bench.

    "You go. I'll watch you," said Alisa.

    "You don't know what you're missing," said Maria. Then she climbed up the tall ladder (梯子). It made Alisa scared just thinking of being up there.

    Maria jumped off the board and then climbed out of the pool. She walled to Alisa. "Come on, Alisa; just try it. It's wonderful!" she said.

    Alisa looked up at the board. Maybe it was time to try something new. OK, she said. Alisa climbed up the ladder for the diving board. The water looked far, far away. She wanted to turn back to climb down the ladder， but that would be too embarrassing. There was only one thing to do.

    Alisa walked to the edge (边缘) of the board. Then she closed (闭上) her eyes and jumped. She got into the water in no time. "Wow, so wonderful! I like it!" she shouted.