Direction: Use the appropriate preposition in the sentence:
What is the time _______ your watch?

In English, when inquiring about or stating the time shown according to a specific timepiece or watch, the correct idiomatic preposition to employ is by (e.g., "What is the time by your watch?" or "It is ten o'clock by my watch"). Using "in" or "on" in this specific phrase configuration is grammatically incorrect.