下列问题中，两个变量成正比例关系的是（　　）

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.

可以用型号为741S14的非门集成电路、发光二极管和限流电阻来组成一个逻辑电平检测器，电路如图所示，使用时，将检测器的输入端A接到被测点．下列说法正确的是（  ）  

①具有规则几何外形的固体一定是晶体      ②NaCl晶体中与每个Na⁺距离相等且最近的Na⁺共有12个

③非极性分子中一定含有非极性键          ④晶格能由大到小：NaF＞NaCl＞NaBr＞NaI

⑤含有共价键的晶体一定具有高的熔、沸点及硬度      ⑥s﹣s σ键与s﹣p σ键的电子云形状相同

⑦含有π键的化合物与只含σ键的化合物的化学性质不同  ⑧中心原子采取sp³杂化的分子，其立体构形不一定是正四面体．