The boy is _________ young to know ________.

Who is your favourite writer?—Mo Yan. He is the first Chinese person _________ wins the Nobel Prize for Literature.

Have you returned the book to him _______? Yes, I have______ returned it.

thecity’spublicschoolsystemshouldbeopentothechildrenofmigrantworkershas become the focus of discussion.

I never thought she would _______ my invitation to the concert. —She would feel sorry for missing the concert someday.