Peter is on . . . . . . . . night duty. When I go to . . . . . . . . bed, he goes to . . . . . . . . work. A. the, no article, a B. no article, no article, no article C. a, a, a D. the, the, no article

The correct answer is: A. the, no article, a

Here is a brief explanation of each option:

• Option A: the, no article, a
  This is the correct answer because it follows the pattern of “on [noun] duty.” For example, you might say “I am on night duty” or “He is on weekend duty.”
• Option B: no article, no article, no article
  This option is incorrect because it does not use any articles. In English, we typically use articles (a, an, the) to refer to specific nouns. In this case, we are referring to a specific type of duty, so we need to use the article “the.”
• Option C: a, a, a
  This option is incorrect because it uses the article “a” twice. In English, we typically only use the article “a” once before a noun. In this case, we are referring to a specific type of bed, so we need to use the article “the.”
• Option D: the, the, no article
  This option is incorrect because it uses the article “the” twice before the noun “work.” In English, we typically only use the article “the” once before a noun. In this case, we are referring to a general type of work, so we do not need to use the article “the.”