watch的過去式是什么為什么

　　He watched the house for signs of activity.

　　他注視著那所房子里的動靜。

　　I watched the car until it was out of sight.

　　我目送汽車，直到看不見為止。

　　We watched the balloon riding high above the fields.

　　我們看著氣球高高地飄浮在田野上空。

　　We watched the lions from the safety of the car.

　　我們從車里看獅子，很安全。

　　I watched the programme from beginning to end.

　　這個節(jié)目我從頭看到了尾。