English verbs have very few forms. And because these forms are not enough to express all meanings, we use auxiliary verbs with other verbs.

Forms such as –ing (as in writing), un- (as in unhappy) and -ful (as in beautiful) are called affixes. The form to which an affix is attached is called its stem. The affix which is added to the beginning of a stem is called a prefix. The affix which is added to the end of a stem is called the suffix. Thus in the word unmistakable, mistake is the stem, un- is the prefix and –able is the suffix. In the word disqualified, qualify is the stem, dis- is the prefix and –ed is the suffix.

Here is a list of phrasal verbs using the word keep.

Keep around

To keep something around is to have it ready for use.

In English, we use several different tense forms to talk about the future. Test your knowledge of these tense forms with this grammar exercise.

Some people use I in expressions like you and I and my mother and I. Note that this is correct only when this phrase is used as the subject of a verb.

Here is a list of phrasal verbs with take.

Take after

To take after somebody is to resemble them.

• The baby takes after his dad.

As the name itself indicates a modifier is a word used to modify another word. A modifier should come close to the word it modifies. If it doesn’t, the result might be funny. Modifiers that seem to modify the wrong word are often called misplaced or dangling modifiers. This is a very common mistake.