1) I think they do.

我以为是这样。
2) I guess it is.

我猜是这样。
3) I don't think it possible.

我以为这不可能。
4) I just think so.

我就是这么认为。
5) Yes, it is, as far as I know.

就我所知是这样。
6) I expect so.

我料想是这样。
参考词条