Lack

Example Usage:

Tonya lacks the necessary skills.
There is a lack of understanding.

Common Mistakes:

I lack of knowledge. (Wrong!)
I lack knowldge. (Correct)

His argument is in lack of substance. (Incorrect)
His argument lacks substance. (Correct)

Explanation:

The word lack can be either a verb or a noun.
It is most commonly used as a verb, followed by an object.
(No preposition is needed.)

Frank lacked common sense. (S - V - O)

When lack is used as a noun, it is often followed by the preposition "of" + an object.

She expressed a lack of trust in his company.

When lack is used as a noun, it is usually singular and preceded by an article.
You will often see it preceded by the phrase "there is/was."

Mr. Krumpy exhibited a lack of good manners.
Suzie was amazed at the lack of eligible bachelors in her class.
There was no lack of tasty food at the buffet table.

When using the word lack, try to avoid excessive wordiness.
In many cases, this means using the word as a verb, not a noun.

The cake is in lack of sugar. (Wordy)
The cake lacks sugar. (Much better)