— It seems that Mr. Wu is standing there.— It ______ be him because he called me from Canada just now.
-Could you tell me________ yesterday? -I went bike riding with my classmates.
The police warned the thief _______again.
I wonder_____ they will pass the exams or not.
The light______ by Edison is helpful for people.
—________do you practice your pronunciation? —I practice it _____ asking the teacher for help.