—— Was that the new comer who walked by?
—— ＿＿＿＿＿.
A.It must be that B.It must have been C.He must be D.This must have been
—— Was that the new comer who walked by?
—— ＿＿＿＿＿.
A.It must be that B.It must have been C.He must be D.This must have been
B
表示对过去情况的猜测，用“情态动词＋have done”；而it代替上文所指的new comer。