Answer:
In "the Lottery", Shirley Jackson builds suspense through frightening foreshadowing and slow pace of the story.
Foreshadowing is a literary device writers use to give a hint about what is going to happen later in the story. For example, when Bill wins the lottery, Tessie seems to be frightened and protests. As winning the lottery is usually a good thing, this serves as a hint that something bad is going to happen to the winner.
Slow pace of the story means that events in the story unfold slowly (not everything is revealed at once) which brings even more tension. Jackson also uses third-person perspective, which means that the readers do not know what the characters are thinking. For example, when the children put the stones in their pockets, we might assume that they are just going to play with it, until the real purpose of gathering stones becomes clear at the very end of the play.