1.so可以用作連詞，表示“因此，所以”。

　　例：I heard some noise outside, so I went out of the room to see why.

　　so that作為連詞詞組，表示 “以便，為了”。

　　例：The vase is put high on the table, so that it won’t be broken.

　　2.so可以用作形容詞，表示“是這樣的，是真的”。

　　例：The newspapers claim she killed him in self defence but that just isn’t so.

　　3.so可以用作副詞，用法如下：

　　1)“如此，這么”結構為：so+adj./adv

　　例：She was so tired that she fell asleep very fast.

　　表示此意思時，還可以用：so+adj.+a/an+n.

　　例：It is so good a movie that everyone who saw it praises it very much.

　　2)“如此，如是”，用于表示已經提到的想法，建議或情況等

　　例：“Will I need my umbrella?”

　　“I think so.”

　　3)“也是，也一樣”結構為so+助動詞/情態動詞/be動詞+主語

　　例：Tony takes exercise every day and so does his younger brother.

　　注意否定句應把so改為neither/nor，結構為neither/nor+助動詞/情態動詞/be動詞+主語

　　例：Jenny has never been late for class.Neither/Nor her younger brother.

　　4)“確實是這樣”，表示對前面陳述事實的強調，結構為so+主語+助動詞/情態動詞/be動詞

　　例：Tony works very hard at all the subjects.So he does.

　　5)“似乎，那么”，表示驚訝、不同意或者嘲諷

　　例：So you think you've got troubles?

　　常見結構：and so on/and so forth：等等;so as to(do)：以便;so that+從句：以便

　　例：We eat different vegetables， such as tomato，potato，celery，and so on.

　　They got up early so as to catch the first bus.

　　They got up so early that they could catch the first bus.