I guess I'd better get going.

我想我得走了。

I'd=I had

had better

不得不

I'm getting drowsy, I think it's time for me to go now.

我有點兒困了，我想我該走了。

I hate to leave, but I have an early day tomorrow.

我不想走，但是明天我得早起。

I suppose we had better hit the road.

我想我們該出發了。

I'm going to take off now.

我現在出發了。

I have to go now, I'm in a rush.

我有點兒急事，我得走了。

I'm afraid we have to leave now.

恐怕我們得走了。

Oh my god, I didn't realize what time it was.

天哪，我都沒注意已經幾點了。

Dialogue1:

A: Oh, look at the time. I must be getting going.

天哪，看看都幾點了，我得走了。

B: Is it that late already?

已經這么晚了嗎？

Dialogue2:

A: Do you have to leave so soon?

你真的這么著急走嗎？

B: I would love to stay, but I really have to get back.

我也想再呆一會，但是我必須回去了。

Dialogue3:

A: I really enjoyed visiting, thanks for having us.

我們這次來訪很開心。謝謝你邀請我們。

B: It's been a pleasure.

我得榮幸。

A: Well, I think I'd better get going.

我想我得走了。

B: Do you have to leave so soon?

這么著急走啊？

A: I promised my son to go fishing tomorrow. So I have to get up early.

我答應我兒子明天一起去釣魚，所以我得早起。

B: Oh, well. Thanks for coming over and bringing the nice wine.

好吧，謝謝你今天能來，還帶來了這么棒的酒。

A: No problem. I think your place is fantastic and the meal was great.

沒什么的，我覺得你家真是太棒了，晚飯也做的很棒。