while i was about to place my order, the waiter left my table and disappeared without pardon. he returned without so much as an apology or explanation as to why he ran away in the first place. later, before the dessert arrived, my wife tried in vain (b) to have / having a refill of coffee. the waiter walked past the table as if we did not exist. i finally had to get up and get the coffee myself. by then, my wife and i considered the evening to be ruined.

(b)번에서 답이 to have 이던데 어떻게 해서 그런가요?그리고 having으로 하면 왜 안되는지 궁금합니다