So, normal sentence you could say " I have a girlfriend" , " I have a boyfriend" , whatever.

你可以说一个正常的句子“I have a girlfriend（我有个女朋友）”，“I have a boyfriend（我有个男朋友）”之类的。

In English, contractions are more common. They sound more natural; they're better, just contractions are better in a normal sentence.

在英语中，缩写更为常见。他们听起来更自然；它们更好用，普通句子中的缩写会更好。

Prose uses normal sentences and paragraphs, right?

散文使用正常的句子和段落， 对吗？

If a guy wants to say to a girl something like " I love you" , that's a normal sentence, right?

如果一个男孩想和一个女孩说“I love you”，这是一个正常的例子，对吧？

A normal sentence would be " I called you last night" , but he's arguing against her accusation of not calling her.

一个正常的回答会是“I called you last night（我昨天晚上给你打了电话）”，他反驳不给她打电话的指控。

But the actual letters that Jenny used were not the same as you would use in a normal English sentence.

但珍妮实际使用的字母与你在普通英语句子中使用的字母不同。

We use the verb like we would in a normal sentence and if the verb is changed to show a tense, that change remains.

动词的使用也和正常句子语序一样，如果动词根据时态变化，这种变化要保留。