A. safe B. maker C. among
—Hey, Jack. You ________ on the phone just now. But you weren’t here and the man left a phone number. —Oh? I was in the library.
—Have you watered the plants yet, Kathy? —Yes. I ________ that this morning.
—Let’s plan a surprise party for our class. What’s your idea?—Why not ________ a short play?
—Will you please answer the door? It ________ be your sister.—Sorry, I ________. I’m feeding the rabbit.
—Jim, is physics difficult to learn in high school? —Sure. No subject can be learned well ________ hard work.