--- Do you know ___ we'll get there at 3:00 this afternoon?--- I am afraid we'll be late.

--- Do you know ___ we'll get there at 3:00 this afternoon?--- I am afraid we'll be late.
单选题 
10.--- Do you know ___ we'll get there at 3:00 this afternoon? --- I am afraid we'll be late. A whether B why C how D that