阅读下列短文，从每小题的三个选项中选出最佳选项。
Hello, I'm Ann. This is my family. There are five people in my family. My grandparents are old. They are teachers. My father is tall. He has a white shirt. He is a fireman. He is not afraid of fire. He can help people. He likes his job. My mother is tall and beautiful. She has long hair. She has a yellow skirt. She is a nurse. I don't have any aunts. What about you?
的部分，然后将甲切去部分叠放在乙的剩余部分上，将乙切去部分叠放在甲的剩余部分上，此时甲对水平面的压强p甲，乙对水平面的压强p乙，甲对水平面的压力F甲，乙对水平面的压力F乙，下列判断正确的是
