A tourist will easily lost his way in Beijing ______ he has a map or guide.
These are my shoes. Yours ______ yellow.
—______ is this?—It's yellow.
There is a police car _____ the bus. The police are watching the traffic.
—Lily, here are your pens. Please _____. —OK, Mom.
—_____ do you have an art lesson? —Four times a month.