—How did it _____ that you made such a silly mistake?

—I myself haven’t figured it out yet.

A. bring about   B. come about  C. come across D. come on

-How did it ________ that you made such a silly mistake?

-I myself haven't figured it out yet．

1. A.
   bring about
2. B.
   come about
3. C.
   come across
4. D.
   come on

---How did it ______ that you made such a silly mistake?
---I myself haven’t figured it out yet.

1. A.
   bring about
2. B.
   come about
3. C.
   come across
4. D.
   come on