Antarctic _____ we know very little is covered with thick ice all the year round.

Mary was born the evening of January 1st, 1996. [ ]

Are there any story-books for students In read in the library?—There are only a few, if _.

Mr. Smith left for London _____ Monday morning. [ ]

Do you know___________ in Ya’an? — On the 20th of April，2013.