---Why does Maria look so tired?---She missed our school bus she had to walk here all the

问题补充：

---Why does Maria look so tired?

---She missed our school bus, she had to walk here all the way.

A. or

B. so

C. but

D. and

答案：

A. or

(答案→)B. so

C. but

D. and

解析：句意：玛丽亚为什么看起来这么疲倦？因为她错过了校车，她不得不走到这里。she had to walk here all the way是she missed our school bus产生的结果，所以选B。