______ he switches on the light, the shadow disappears?
Answer Details
The correct option to complete the sentence is "Whenever." "Whenever" is a conjunction that means "every time that" or "on every occasion when." In this sentence, it indicates that every time the person switches on the light, the shadow disappears. The word "expect" means to anticipate or look forward to something, so it doesn't make sense in this context. "Since" is used to indicate a point in time or a cause and effect relationship, but it doesn't fit in this sentence. "Until" is used to indicate a time or event up to a certain point, but it doesn't convey the idea of a repeated or habitual action like the other options. Therefore, the correct answer is "Whenever."