The correct answer is you shall have taken. Key Points In the sentence, 'shall' is incorrect 'Shall' is used for future tense but the sentence is in the past tense. 'Should' is the past tense of 'Shall'. The correct word must be 'should'. Hint In error-type questions, we first look for grammatical errors if any and then vocabulary based errors. ​Additional Information Whenever 'Having' is used as a subject, past participle of the verb follows it. 'Begun' is the past participle of the verb 'begin' and 'began' is the past tense of the same verb. ​So the correct sentence is - Having worked for the whole day, you should have taken some rest and begun again.