We should respect food and think about the people who don't have ______ we have here and treat

food nicely.[ ]

A. that  

B. which

C. what  

D. whether

急性感染性喉炎表现为________呼吸困难，支气管哮喘表现为________呼吸困难。急性喉炎，_______情况需要气管切开。