They decided to leave the waiter a big because the food and service had been excellent.A.

问题补充：

They decided to leave the waiter a big because the food and service had been excellent.

A. note

B. reward

C. tip

D. gift

答案：

A. note

B. reward

(答案→)C. tip

D. gift

解析：tip 本题中意为“小费”符合句意。