---Look at the boy running on the playground. Is it David? ---It ______ be him. I saw him go to the teachers’ office just now.
George said that he would come to school to see me the next day, but he.
Jerry did not regret giving the comment but felt ______ he could have expressed it differently.
One learns a knowledge by making mistakes and ______ them.
By the time you have finished this book, your meal ______ cold.
-Look at those clouds! -Don't worry. ______ it rains, we'll still have a great time.