Normally, after the interview, the interviewer should ask :
Do you have any question? or Well!!! is there anything furthure you would like to know? In this case, this is a good opportunity for the applicant to ask 2-3 questions to show that you are really interested in the work. For example :

What does the probation period involve?
Is there any traing given? & How long is the period of training
What does the training course consist of?
What should be the responsibilities of this work/
Does the company have any plan to expand?
How do you assess the employees' working performance?
What new products is the company planning to introduce that will support future growth?
Why isn't this position being filled from within the company?
To what positions would I likely progress? Why?
Does the company support additional formal education? What from does such support take?
What else can you tell me about opportunities for promotion and advancement?
What improvement would you like to see in this areas?