<span>The most significant characteristic of Cassius is his ability to perceive the true motives of men. Caesar says of him, "He reads much; / He is a great observer and he looks / Quite through the deeds of men." The great irony surrounding Cassius throughout the play is that he nullifies his greatest asset when he allows Brutus to take effective control of the republican faction.</span>
A prepositional phrase is such a phrase which begins with a preposition (on, under, over, etc) and ends with a noun, pronoun, gerund, phrase etc.
So here, the correct sentence will be "On the stage the members of the orchestra began to tune their instruments".
.--. . . .--. . . .--. --- --- .--. --- ---
Is there anyone by whom this room is being used today?
Passive voice is a sentence where the object undergoes the action.
Here, the object is the room, and the subject is if it's being used by anyone.
Hope it helps. :)
