若元素a,b,c,d,e,f依次进栈,允许进栈、出栈操作交替进行,但不允许连续三次进行出栈操作,则不可能得到的出栈序列是()
A. d,c,e,b,f,a
B. c,b,d,a,e,f
C. b,c,a,e,f,d
D. a,f,e,d,c,b
Which is the correct serving orders for a typical western dinner()
A. appetizersoupmain coursesalad dessertcoffee or tea
B. soupappetizermain coursedessertsalad coffee or tea
C. appetizersoupmain coursesalad coffee or teadessert
D. appetizermain coursesoupsalad dessertcoffee or tea