________ you happen to see Mary, would you please ask her to come here?
It is hard to say what kind of person he is. Sometimes he is very friendly; at other times he ___ be very cold.
Doing your homework is a sure way to improve your test scores, and this is especially true ____ it comes to classroom tests.
—“Do you mind if I look at your notes?”—“Of course not. _______.”
Afghans used to hold big weddings, costing thousands of dollars, in a county _____ the average annual income is less than $400.
She ought to stop work; she has a headache because she ___________ too long.