根据下列句子及所给汉语注释，在横线上写出空缺处各单词的正确形式。（每空只填一词）
51. Are you _________(熟悉) with the song he is singing?
52. Try to ________(简化) your idea and tell me.
53. The_________ (接线员) has got me through to Beijing
54. Each of us has a ______________(计算) machine
55. My teeth are very____________(敏感的) to cold food.