— Would you like to stay for another two days?  

— Sorry, I ____. One of my best friends is coming to see me.  

A. mustn't  

B. can't

C. needn't

D. ought not to

能导致夜盲症是由于长期缺乏（），儿童可引起佝偻病，成人则易患骨质软化病是由于缺乏（），缺乏（）易患脚气病，缺乏（）主要表现在眼、口腔、皮肤的炎症反应。