Mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the following questions

The preparation_________ by the time the guest_________

A. have finished- arrived

B. had been finished- arrived

C. had finished-were arriving

D. have been finished- were arrived

Giải sử n - 3 và n + 7 đều chia hết cho số nguyên d ( d \(\ge\) 1 ) với n \(\ne\) -7

=> n - 3 \(⋮\) d và n + 7 \(⋮\) d

=> (n + 7) - (n - 3) \(⋮\) d

=> 4 \(⋮\) d với d \(\in\) Z

=> d \(\in\) {4}

=> n - 3 \(⋮̸\) 4 ; n + 7 \(⋮̸\) 4

=> n \(\ne\) 4k + 3 ; n \(\ne\) 4k - 7

Vậy: n \(\ne\) 4k + 3; n \(\ne\) 4k - 7 ( n \(\ne\) -7)