语句if(x>0) x=(a-b/2)*c对应的四元式序列为()。
A.(1) (> x 0 t1) (2) (if t1 _ 6) (3) (/ b 2 t2) (4) (- a t2 t3) (5) (* t3 c t4) (6) (= t4 _ x) (7) (ie _ _ _)
B.(1) (> x 0 t1) (2) (if t1 _ 7) (3) (- a b t2) (4) (/ t2 2 t3) (5) (* t3 c t4) (6) (= t4 _ x) (7) (ie _ _ _)
C.(1) (> x 0 t1) (2) (if t1 _ 7) (3) (/ b 2 t2) (4) (- a t2 t3) (5) (* t3 c t4) (6) (= t4 _ x) (7) (ie _ _ _)
D.(1) (> x 0 t1) (2) (if t1 _ 7) (3) (/ b 2 t2) (4) (- a t2 t3) (5) (* t3 c t4) (6) (= x _ t4) (7) (ie _ _ _)