Usually, both words are underlined or italicized.是什么意思？

Usually, both words are underlined or italicized.

通常情况下, 这两个词都强调或斜体.

usually

adv. 通常，经常，平常，惯常地，一直，向来，动不动，一般，素；

例句
In Europe, AC is usually generated at 50 Hz.
欧洲的交流电输出频率通常为50赫兹。

both

adj. 二者，两者都；pron. 二者；adv. 二者，二者都；conj. 不仅…而且…，…和…都；

例句
The gym can be used by both able-bodied and disabled people.
这家健身房健全和残障人士都可使用。

words

n. 字( word的名词复数 )，（说的）话，诺言，口令；

例句
She felt as if his words had granted her absolution.
她感觉他的那番话好似给她下了道赦令。

are

vi. （用于第二人称单复数现在时，第一、三人称复数现在时）是；n. 公亩（等于100平方米）；

例句
We are scared to abandon ourselves to our feelings in case we seem weak or out of control.
我们不敢放纵自己的情感，以免显得太过软弱或缺乏自制。

underlined

v. 在…下面画线( underline的过去式和过去分词 )，加强，强调；

例句
How badly the administration had lost its bearings was underlined by what happened yesterday.
管理之差从昨天发生的事情就可见一斑了。

or

conj. 或，或者，还是，不然，否则，左右；prep. <古、诗>在…之前，比…更早；n. [纹章]黑金色、黑色；

例句
We are scared to abandon ourselves to our feelings in case we seem weak or out of control.
我们不敢放纵自己的情感，以免显得太过软弱或缺乏自制。

italicized

v. 用斜体字排字，在字下划横线( italicize的过去式和过去分词 )；

例句
Look up the dictionary and explain the meaning of the italicized words.
查字典然后解释斜体词的意思.