As I was worried about the safety of my son in the heavy storm, my attention began to _______ off my work.
______ the cold, thin air and low oxygen levels also can cause mountain sickness.
China is a wonderful land ______ minerals.
_______, when I went to town to see my sick teacher, he said to me, “I’ll come back to school again _______.”
Sweet memories ______ as I looked at the pictures _____were taken at the beach last summer.
Dr Yuan makes______ possible______ one-third more of the crop in the same fields.