A:Na2SO4 KNO3 Na2CO3 NH4Cl
B:H2SO4 BaCl2 Na2SO4 NaOH
C:MgCl2 AgNO3 KNO3 HCl
D:NH4HCO3 NaOH NaCl HCl
根据短文内容,选择正确答案。
Here is a photo. The two girls have big blue eyes and long brown hair. They are both ten years old. They are in the same class. The one in a yellow skirt is Lily. The other one (另一个) an orange skirt is Lucy. Their father (父亲) is Mr. White. He is in a brown coat. Their mom is Mrs. White. She is in a black dress. Who is that boy in a blue cap? He is Lucy and Lily's brother(哥哥), Bob. He is a high school student. Look! Lucy and Lily are in a green car.
一块均匀的长方体砖块,分别按图2所示甲、乙、丙三种方式放置在水平地面上,其中对地面压强最大的放置方式是( )