题目内容
(请给出正确答案)
[单选题]
According to structure, which kind of sentence does the following sentence belong to? Mary and Samantha left on the bus before I arrived, so I did not see them at the bus station.()
A.Simple
B.Compound
C.Complex
D.Compound-complex
![](https://lstatic.shangxueba.com/sxbcn/h5/images/tips_org.png)