How can I align Node B and Node D and Node F horizontally?

[CodeZHXS]

Hey guys, I just started learning how to use Mermaid.
Here is my code：

classDiagram
    A <|--B
    B <|--C
    D <|--E
class F

How can I align Node B and Node D and Node F horizontally?

[CodeZHXS]

Am I missing some syntax?