Question

Fill in the blanks with the most appropriate word.
He ___________ for half an hour when he realized he was painting the wrong wall.
A. Worked
B. Had worked
C. Has worked
D. Has been working

Answer 1

Hint:A verb-based technique used in reference to the time of expression to signify the time, and often the continuity or completeness, of an event or condition. In English, the idea of tense is a tool we use to apply to time - past, current and future.

Complete answer:
'Was' and 'realized' in the given sentence means that the tense of the sentence is past tense. The statement further suggests that the action in the blank was already complete with regard to the past after which the author was conscious. Therefore, to signify an event completed with respect to the past, the answer must be in the past perfect tense.
Choice A is unreliable. In the plain past tense and not the past perfect tense,' worked' is. Using it would then render the tense of the sentence contradictory.
Choice B is reliable. 'Had performed' was the perfect tense of the past. Thus, it means that with reference to the past, the working action was done. It is, thus, right.
Choice C is unreliable. In the present perfect tense,' has worked' is not the past perfect tense. Using it would then render the tense of the sentence contradictory.
Choice D is unreliable. 'has been working' is in the perfect continuous tense of the present and not the perfect tense of the past. Using it would then render the tense of the sentence contradictory.

Hence the correct answer is option B.

Note:There are four elements of the present, past and future tenses:- the simple, progressive, perfect and perfect progressive. There are twelve main verb tenses which signify time and expression.