单项选择题A.In bamboo chairs.B.On bamboo mats.C.On the floor.D.On knees.
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.