YOU SAID:

How does this thing work, it must be complicated

INTO JAPANESE

これはどういう仕組みなのか、複雑なものに違いない。

BACK INTO ENGLISH

It must be a complicated question of how this works.

INTO JAPANESE

これがどのように機能するかという複雑な質問に違いありません。

BACK INTO ENGLISH

It must be a complicated question about how this works.

INTO JAPANESE

これがどのように機能するかについての複雑な質問に違いありません。

BACK INTO ENGLISH

It must be a complicated question about how this works.