Although it was not suited to solving his immediate problem, Silver felt the unusual adhesive might have some commercial value, and so he demonstrated it to various colleagues, including Fry. At the time, no one had come up with a use for it, and so the formula for the weak adhesive was filed away – until the Monday morning when Fry came to work with the idea of making sticky bookmarks that could also be removed without damaging the book. —The Evolution of Useful Things, Henry Petroski Which pair of phrases signals the passage of time? Although it was not suited . . . Silver felt. . . . Silver felt . . . and so he demonstrated it. . . . At the time . . . until the Monday morning. . . . . . . until the Monday morning . . . that could also be. . . .

c) At the time...until the Monday morning

Explanation:

Time is one of the story's setting parts. It is important to know when something happened, when it finished, how long it lasted etc.

Time period can be as only as few minutes long, but it can only stretch up to few years. This can be helpful in setting the story's dynamics.

In order to know about the passage of time, we need to have at least two "time stamps".

In this particular excerpt, we have "at the time" denoting a moment in time when no one found he use for the adhesive, and "until the Monday morning" denoting another moment in time, different from the previous, when Fry came up with the idea for the use of the adhesive.

These two phrases signal the passage of time since they denote two different moments in time.