单项选择题A.Time.B.Memory.C.Habit.D.Text-book.
单项选择题A.7 years.B.9 years.C.12 years.D.16 years.
单项选择题A.Taking off his shoes.B.Washing his hands in a pool.C.Washing his hands in a stone basin.D.Bowing to the hosts.
单项选择题A.Planktons are too small to be seen.B.Most planktons have transparent tissues.C.Most planktons are practically invisible to predators.D.Planktons are fascinating organisms.
单项选择题A.Four contestants failed to win prizes.B.The man ate during the show.C.The woman missed the show.D.Five contestants won cars.