现有a、b、c三束单色光，其波长关系为.用b光束照射某种金属时，恰能发生光电效应.若分别用a光束和c光束照射该金属，则可以断定

用方框中所给的句子填空。请将正确答案的序号填在题后横线上。

Receptionist: ____  Madam?
Alice: I want a single room. I booked（预定）it three days ago.
Receptionist: ____ .
Alice: It’s Alice. Alice White.
Receptionist: Oh, yes. Here it is. You want a single room.
Alice:____  And if it is possible, I’d like a room on the ground floor.
Receptionist: ____  all the rooms on the ground floor have already been taken. But we do have a nice room that overlooks the hotel swimming pool. It is on the second floor.
Alice: Thank you. ____  is the restaurant still open?
Receptionist: I’m afraid not. But you can order room service.
Alice: OK. Thank you

“从中国经济史看来，左右经济发展情况的主要因子，是政府对经济事务干预的有无与多寡。”“凡政府干预愈深者，则市场机能运作能力愈弱，反之亦愈强。”（台湾学者侯家驹撰写的《中国经济史》）下列对材料理解最准确的是（   ）

走进名著：                                                                                                                                                                              

已知圆的方程为.设该圆过点（3，5）的两条弦分别为AC和BD，且.则四边形ABCD的面积最大值为（     ）