31.—Can you tell me what time the flight to Detroit leaves? —I'm sorry, but it ______.
Paper cuts which show the Chinese character for double happiness are often used ________ weddings.
Many children, parents are away working in big cities, are taken good care of in the village.
From the top of Mount Tai, you can get a wonderful of sunrise.
____ the morning of my mother’s birthday, I usually help my mother do some housework.
----What’s that building made of? ----____________, I think.