what's your plan for vacation?这句话中的plan 为什么不用plans

what's your plan for vacation?这句话中的plan 为什么不用plans what are your vacation （ ）【plan】可以用plans么 What's your plan for the coming vacation?I _________(fly) to What's your plan for the afternoon? -what's your plan for this weekend? What's your plan of this summer vacation什么意思 Could you tell me, what's your vacation plan? what do you plan for tomorrow?what are your plans for tomorr What do you plan-----your vacation? What is Lin Hui's vacation plan 英语翻译he plan to go to italy for the coming vacation.这句话对吗?为什么 7.What’s your plan for your Spring Festival?