Student or Learner
1. I did n't know there are minefields.
2. I never knew Egypt was so large.
3. I never knew you had a twin sister.
Sentence 1 comes from BNC, and sentences 2 & 3 come from OXFORD. I'd like to know if the present simple is correct in the object clause and can be used safely.
Could I ask native English teachers to help me please? Thank you very much.