◎ 题干
      I walked into class, the teacher had started teaching already.        
[     ]
A. By the time  
B. While        
C. After            
D. Because
◎ 答案
查看答案
◎ 解析
查看解析
◎ 知识点
    根据n多题专家分析,试题“I walked into class, the teacher had started teaching already.[ ]A. By the time B. While C. AfterD. Because…”主要考查了你对  【介词短语】  等知识点的理解和应用能力。关于这些知识点的“档案”,你可以点击相应的链接进行查看和学习。