单选题 I was ______ in my reading, and didn't at first hear the doorbell ring.

【正确答案】 B
【答案解析】[解析] immured“监禁，禁闭”；immersed“沉浸，使陷入”；be immersed in“专心于，沉浸于”；busy“忙碌”；be busy doing“忙于做某事”；infatuated“昏头昏脑的，使入迷”。答案是B。