It says that the ten horns are ten kings:

Revelation 17:12 And the ten horns which thou sawest are ten kings, which have received no kingdom as yet; but receive power as kings one hour with the beast.

But it doesn't say that the seven heads are seven kings?

Doesn't it say, rather, "and there are seven kings"?

Revelation 17:9 And here is the mind which hath wisdom. The seven heads are seven mountains, on which the woman sitteth.

  10 And there are seven kings: five are fallen, and one is, and the other is not yet come; and when he cometh, he must continue a short space.

Otherwise, if it said that the seven heads "are" seven kings, then what about the five that are fallen?

In that case, would five of the heads then be hanging down, like dead?

But are not all seven heads up and active, upon the beast?

Also, considering that five kings had fallen, what time period do the seven kings represent?

From Abraham until the end?

From Moses until the end?

During the times of the Gentiles?

During the church age?

Or only at the end?

Is the short space that the seventh continues, for 42 months, or is it only up to the mortal head wound?