Unfamiliar use of 得.

[mc1003]

I've learned all the basic uses of 得, but in a fairly intermediate level textbook, I keep seeing uses of 得 that I haven't seen before and I don't understand why the 得 is there. Here are a few examples:

我不但得跟他们一块活动。。。

每天还是得上学校。

现在开学了，又得开始学习。

In each of these sentences, based on what I've learned thus far, I would have written the sentence without the 得 and thought that it was grammatically proper. What am I missing?

Thanks!

[Olle Linge]

You're missing that 得 can be read "dei3" and means "have to" or "must", perhaps?

[Radzilla]

The above poster is correct. In every example provided, 得 takes on the reading dei3 and means "must".

I remember when I was first learning this word and tried using it with my friend from Taiwan. He kinda laughed at me, I guess this particular use of 得 is not popular in Taiwan.