餐厅服务的四项基本环节是餐前的准备工作、（）、就餐服务、餐后服务。
参考答案：迎宾服务
请将下列句子单复数互换。
1. This is a butterfly.
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2. Those are white sheep.
3. This is her child.
4. These apples are big.
5. That is a gray mouse.
若0＜a＜1＜b，则[ ]
A、a2+b2＜a3+b3
B、a2+b2＞a3+b3
C、logab+logba≥2
D、logab+logba≤-2
