Pronouns are any words in the English language that can take the place of nouns. While they may be simple and straightforward to use, many students (including native English speakers) tend to use the incorrect pronoun in both writing and speaking:

     Each person must pay $25 before they could enter.

     Craig has several pens. It is black.

In the first example, each person is third-person singular, so the correct pronoun should be he or she:

     Each person must pay $25 before he or she could enter.

In the second example, several pens is third-person plural, so the correct pronoun should be they:

     Craig has several pens. They are black.

A comparative is a syntactic construction that serves the purpose of comparison. Here are some examples:

     George is taller than Michael. (Compares George and Michael)

     This new sponge is more absorbent than the old one. (Compares the new sponge to the old one)

Note that for comparatives where the suffix -er is added to an adjective, there is grammatically incorrect to add more in front, as is the case in the first example. The reason it is because a word like taller by itself already means more tall, which makes it unnecessary to put more in front. As such, the following example would be grammatically incorrect:

     Jenny is more older than Annie.

The way we correct this would be to simply take out the more in the sentence:

     Jenny is older than Annie.

What is the difference between the past perfect and the simple past? Have a look at the examples below:

The simple past looks like this:

     I finished my homework.

     A tree fell down.

The past perfect for the sentences above would look like this:

     I had finished my homework.

     A tree had fallen down.

The past perfect is essentially the verb had followed by the past participle, which in the examples above, are finished and fallen respectively.

When indicating a past action, we use the simple past tense, but when we try to show that an event happened before another event happened, we use the past perfect tense. In other words, the first event is the one in the past perfect tense:

     Jared had saved his work before his computer crashed.

​     Lisa had completed a degree in psychology before she went to law school.

Prepositions in the English language are used for expressing relations in time or space. Common ones include in, of, on, under, above, below, and many more. Here are specific prepositions that we use for indicating relations in time:

To indicate times of day, we use at:

     I leave for school at 8 a.m. everyday.

For days of the week, the proper preposition is on:

     I will be going to my friend's birthday party on Saturday.

When mentioning a year, it is in:

      The Second World War ended in 1945. 

If a specific date is used, the proper preposition is on:

     On December 7, 1941, the Imperial Japanese Navy attacked Pearl Harbor.

When referring to a period of time, use during:

     The Industrial Revolution happened during the mid to late 19th century.

     During the Great Depression, the Roosevelt Administration created many new types of welfare.

Pluralization applies to all nouns that are countable. In most (although not all) cases, the suffix -s (or -es in some cases) appears at the end to signal pluralization. Although seemingly very self-explanatory, pluralization in actuality does tend to be neglected more commonly than we think:

     Several students forgot their book today.

     When it is hot, we need to drink plenty of water to keep our body hydrated.

In the first example, unless the students all use the same physical copy of a particular book, then it should be books. Similarly, in the second example, every person has a different body, so we should pluralize body:

     Several students forgot their books today.

     When it is hot, we need to drink plenty of water to keep our bodies hydrated.

Pronouns refer to those words that can take the place of nouns. The following are subject pronouns, which as the name suggests, are used to indicate subjects of sentences:

     I (First-person singular)
     You (Second-person singular)
     He/she/it (Third-person singular)
     We (First-person plural)
     You (Second-person plural)
     They (Third-person plural)

Each of the above also has an object-pronoun equivalent:

     Me (First-person singular)
     You (Second-person singular)
     Him/her/it (Third-person singular)
     Us (First-person plural)
     You (Second-person plural)
     Them (Third-person plural)

Although this may be very self-explanatory, many students do misuse object pronouns as subject pronouns or vice versa, as in this example below:

     Johnny and me are finished our homework.

Me is a subject pronoun, yet it is incorrectly used as the subject here. The proper way to write this sentence is:

     Johnny and I are finished our homework.