You may call on me from one to five o'clock, during ______ I am always at home. [ ]

A. the time      

B. what time

C. that time    

D. which time

冬天，家中的热水瓶常常会出现跳塞现象，这是由于               [ ]    

A. 瓶内水蒸汽气压减小的缘故            

B. 瓶外大气压减小认得缘故

C. 瓶内水蒸气膨胀对瓶塞做功的缘故      

D. 以上三种情况都有可能