had begun是什么時(shí)態(tài)

　　He had begun to feel sleepy.

　　他已覺(jué)得困了。

　　Rain had begun to streak the windowpanes.

　　雨已開(kāi)始在窗玻璃上留下條痕。

　　Already the allure of meals in restaurants had begun to pall.

　　餐館里飯菜的吸引力已經(jīng)變得平淡了。