C

    My name is Lin Tao. I am a Chinese boy. Now I'm studying in America. There are many kinds of clubs here. When I first come here, I don't know anything about clubs. I'm a shy boy, so I can't speak English well. In my first year in America, I don't like to speak to others. In my second year I have to change (改变) myself by doing some new things. I realize that school is not just about getting good grades (成绩), it's also about being part of a club. One day, when I go to the Media Center with my classmate Jim, he tells me something about the club. It's interesting, so I join it. I am in many clubs now. It's good to be part of a club. These clubs help me to make new friends.

①②③④⑤是使用操作显微镜的几个步骤。如图为显微镜观察中的两个视野，其中标注为黑色的细胞为主要观察对象。由视野(1)到视野(2)时，操作过程正确顺序是(　　)

①转动粗准焦螺旋　②转动细准焦螺旋　③调节光圈④转动转换器　⑤移动玻片

东南亚地处亚洲与大洋洲、太平洋与印度洋之间的“十字路口”,扼守这个十字路口“咽喉”的是(　　)

A.1s²2s²2p⁶3s²3p⁶3d⁵4s²　B.1s²2s²2p⁶3s²

C.1s²2s²2p⁶　D.1s²2s²2p⁶3s²3p²　E.Ar4s¹。

请用元素符号回答下列问题:

回答下列问题：