Li Qinmei lives in Zhucheng, Shandong Province. She lost her 1 at three. Four years later, her father couldn't 2 after an accident. After the death of her grandmother, 12-year-old Li Qinmei had to support her broken family.

    Qinmei learnt to 3 and live a life with 24 yuan per month from the government. The most 4 things she had to deal with were to 5 her father wash, dress and use the toilet as he could hardly move.

    During most of her junior school years, she went to classes 6 once a month as her father was seriously ill at that time. “I taught 7 at home and asked teachers for help on my school days,” she said.

    Though she had a hard life, the difficulties taught her to be 8. “My classmates have both Mum and Dad to 9 them. How happy they are! However, I don't feel 10 as I still have my dear dad and many kind people with me. I believe I will go to college,” she said.

为了探究免疫的产生，某中学生物兴趣小组做了以下试验。

步骤一：取八只小白鼠做实验，平均分成甲、乙两组。

步骤二：甲组的小白鼠取活的肺炎球菌注入体内．乙组的小白鼠取加热杀死的肺炎球菌注入体内，两周后再取活的肺炎球菌注入体内。

步骤三：观察实验结果．甲组的小白鼠死亡，乙组的小白鼠存活。

请回答以下问题：

在边长为2的菱形ABCD中，∠BAD=120°，则$\overrightarrow{AC}$在$\overrightarrow{AB}$方向上的投影为（　　）

下列操作可以达到实验目的的是（   ）