～そうな/そうに

今にも なきだし （ ）かおを しています。
a. そうな b. そうに c. ような d. ように

The intended meaning is: She looks as if she is about to burst into tears. She hasn’t started to cry but she looks she is about to, so the correct answer is a. そうな.

[verb stem] + そう

The usage of this そう is the same as あめがふりそうです, which is explained here. When そう is used with the stem of a verb, it can express your judgement something is about to happen.

いいことがありそうな日ひです。
It looks like a day when something good will happen.

そのしょうせつは ほんとうに おこりそうな できごとの はなしです。
That novel is about something which is likely to happen in real life.

[adjective stem] + そう

When そう is used with the stem of an adjective, it can express how the situation appears to you.

おもしろそうな ほんを 見つけました。
I found a book which looks interesting.

まあ、まじめそうな ひとですね。
Wow, he is such a serious looking bloke, isn’t he?

In the above examples, そう part is explaining the underlined nouns, so そうな is used.

In the next examples, そう part is explaining the underlined verb, so そうに is used.

ジョンさんは なんでも おいしそうに たべます。
John eats everything deliciously.

エマさんは うれしそうに わらっていた。
Emma was laughing happily.

いつもは ふざけているのに、きょうは まじめそうに すわっている。
Although he is always fooling around, he is sitting down seriously.

いかにも満足（まんぞく）そうに眠（ねむ）っている。
He is sleeping with evident satisfaction.

今（いま）にも雨（あめ）が降（ふ）り出（だ）しそうに見（み）える。
It looks as if it is about to rain.

おもしろそうに きこえたよ。
It sounded like fun!

For more study material for JLPT N4 exam, please visit JLPT N4 Grammar and Vocab and JLPT N4 Kanji pages.