When to use 'that'?

其實你兩句句子都可以用that，也可以不用that。只不過用that時，是比較正式。
我們經常可以省略連接詞that，特別是在非正式的文體中。以下是幾種情況，我們可以省略that
１．間接引語
　　在許多後面可以用that－子句的動詞，在非正式場合，that可以省去。如：（注括號的that可以不要）
　　James said (that) he was feeling better.
　　I thought (that) you were in Ireland.
　　但在某些動詞（如reply, telegraph, shout）後面that不能省略，如：
　　James replied that he was feeling better.（不能說：James replied he was feeling better)
２．在形容詞後面
　　I am glad (that) you're all right.
３．連詞
　　一些常用的雙詞連詞，如：so that, such...that, now that, providing that, provided that...其中的that在非正式文體中可以省去
I was having such a nice time (that) I did'nt want to leave
４．關係結構
　　當關係代詞that在關係從句中作賓語時，通常可以省去。
如：Do it the way (that) I showed you.

希望幫到你！（但若是作文，勸你用that，因包保無錯）