We'll hold a party in celebration of the 90th birthday of the CPC (中国共产党)_________ Friday.A. in B. on C. at
--How much are these pants? --_______ twenty dollars..
A: _____is Mary? B: I think she is at home.
Some ________ are on the table.
Thanks _____ the photo of your family.
Is your photo in the desk? ________.