hadbegun是什麼時態

The window frames had begun to warp.

窗框已經開始變形。

He had begun to feel sleepy.

他已覺得困了。

The gold colouring had begun to rub off.

金黃色已經開始剝落了。

She had begun to be a little bored with novel writing.

她開始對寫小説有些厭倦了。

The blood had begun to cake and turn brown.

血開始結塊變黑。