--- Where did he leave his car key? --- It was in the lab he made the experiment.
_____ the city’s public school system should be open to the children of migrant workers has become the focus of discussion.
—You may find the key to the math problem on page 107. —Ah, it's so simple. I wonder why I _____ of that.
Cars do cause people some health problems, in fact far more serious _____ than computers do.
More people are choosing to work _____ retirement age,since the living expenses are shooting up sharply.
On seeing_____ gift they wanted, the kids screamed with _____ delight.