1. What caused the serious traffic accident remains (remain) unknown.
2. It is a pity that we won’t be able to go camping this Sunday.
3. Whoever pollutes (pollute) the environment will be punished.
4. That we shall be late is certain.
5. It is not sure whether he will come to your house or not.
6. (2019·全国卷Ⅰ)The deadlines and what you need to apply depend on the program.
7. (2019·全国卷Ⅰ)What you need is a great teacher who lets you make mistakes.
8. (2018·全国卷Ⅱ)It’s possible that we all have compromised conversational intelligence.
9. It’s more likely that none of us start a conversation because it’s awkward and challenging, or we think it’s annoying and unnecessary.
10. It is a fact that the earth is round.
