If you are not familiar ____ the topic, you may write something that is familiar ____ you.
29. Please ______ your sister to bring the ticket for the concert.
28. Be careful! The slightest spark(火花)could ______ the fireworks.
27. The police are offering a $ 60,000 _____ for information about the killer.
26. People generally think that smoking is a bad ______ .
25. We invited her to dinner but she didn’t even bother to _______ .