Peter ________ at this job since he graduated from college.
It is the test system, _______ the teachers, that is to blame for the heavy burden of middle school students nowadays.
This is a difficult and stressful job, but one _____ you can really help people.
A feather falls slower than a stone only because the air holds the feather back more than it ______ the stone.
The old black woman used to tell stories under the tall tree, her grandchildren ______ around and ______attentively.
According to _______ recent report, large ice cream producers usually have better production record.