1£®What he will say at the meeting is not known to us.

2£®I wonder who/whom that letter was from.

3£®Give me one reason why we should help you.

4£®Whether he can finish it in two hours is a question.

5£®I'd asked everyone but only two people came.

6£®The little girl can tell right from wrong although/though she is only twelve.

7£®Work hard£¬or you'll fail the exam.

8£®How do you know that?

9£®It's most likely that he will succeed.

10£®He cheered up at once when I promised to help him.