实验室制取乙烯的装霣如图1所示，
在地球仪上，指示东西方向的是____线，它与地轴____，并环绕地球一圈，其长度的变化规律是由赤道向两极____，到两极成____。
从方框中选择最佳选项完成对话, 有两项多余。
A. Are these your parents?
B. Who is the boy on the left?
C. What’s your father’s job?
D. What’s this?
E. Is your mother a teacher?
F. Is this beautiful girl your sister?
G. What’s your father’s name?
Li Lei—L; Mary—M
L: Good morning, Mary.
M: Good morning, Li Lei.
L: ____
M: It's a photo of my family.
L: Oh. ____
M: Yes, she is. Her name is Lily.
M: Yes, they are.
M: He is a doctor.
M: No, she is a nurse.
在一高度处同时释放一片羽毛和一个玻璃球，玻璃球先于羽毛到达地面，其最根本的原因是因为（ ）
