题干
---Excuse me. Can I take a seat here?
---__________. The woman who sat here will be back soon.
---__________. The woman who sat here will be back soon.
A：We’d better not.
B：No, thank you.
C：Yes, please.
D：I’m afraid you can’t.
答案(点此获取答案解析）
D
力相等、长度不等的细线AO、BO，如图1-6
7所示悬挂一个中空铁球，当在球内不断注入铁砂时，则（ ）
