单项选择题
A. At least once a month. B. At least twice a month. C. At least once a year. D. At least twice a year.
A. Rat flea. B. Cat flea. C. Dog flea. D. Rabbit flea.
A. At least 59 people were injured. B. Skyscrapers in Tokyo were destroyed. C. Power to about 17,000 homes was knocked out. D. High-speed train service was suspended.