

James, who is one of our bravest men, never loses his temper; and if he ___ so tense during the Friday night operation the situation must have been extremely dangerous indeed.
A. were
B. was
C. had been
D. has been
Câu nào đúng thì giải thích cho em vì sao lại chọn câu đó ạ?
A. were
B. was
C. had been
D. has been
Câu nào đúng thì giải thích cho em vì sao lại chọn câu đó ạ?