The present participle is used with the verb to be to form the continuous tenses. For instance, a few continuous tenses of to avoid include are avoiding, was avoiding and has or have been avoiding.

But, the present participle can also act as a gerund or an adjective. Consider the verb to sing. The present participle is singing.

Listen to an example of singing as a gerund:

Singing is my favorite activity.

As an adjective:

The singing man was happy.

And as part of a continuous verb tense:

The man was singing in the rain.
verb + gerund

One common situation in which two -ing words can appear next to each other is when the first -ing word is part of a continuous verb tense and the second -ing word is a gerund, as in the first example:

I’ve been avoiding going to the doctor.

Here, have been avoiding is the present perfect continuous form of to avoid. Going is the gerund.

Here’s another example:

I’m considering buying a home in DC.

Here, am considering is the present continuous form of the verb to consider. Buying is the gerund.
go + gerund

Two -ing words can also appear together in what we call “go + gerund.” Go + gerund is an example of the verb + gerund construction.

In English, we add the verb to go to certain recreational activities. These activities include fishing, swimming, shopping and skating, plus more than a dozen more.

Because of this, when go is in the continuous verb tense, you will see two -ing words together.

Listen:

I’m going shopping in Alexandria next weekend.

In this sentence, am going is the present continuous form of the verb to go and the gerund is shopping.

Here’s another:

We’re going skating on Friday in the sculpture garden.

In this sentence, are going is the present continuous form of the verb to go and skating is the gerund.

Note, however, that you will not see two -ing words together when go is not in the continuous tense with these activities. For example: “We went skating in the sculpture garden last Friday” is still part of the go + gerund structure.
verb + adjective

Another English construction in which two -ing words commonly appear next to each other is the verb + adjective structure.

Listen to the example:

The noise is becoming irritating.

In this example, is becoming is the present continuous form of the verb to become and irritating is an adjective that describes the noun noise. Here's another:

I’ve been hearing disturbing stories about that place.

In this example, have been hearing is the present perfect continuous form of the verb to hear and disturbing is an adjective that describes the noun stories.
three -ing words

You may be surprised to know that, in English, it’s also possible to put three -ing words together.

Listen to an example:

We’re considering going fishing near Providence or Newport.

No one would look at you strangely if you said this because it sounds natural in English.

In this sentence, are considering is the present continuous form of the verb to consider. And, going fishing follows the go + gerund construction.

But, if you wanted to express the same meaning in another way, you could say, “We’re thinking about going fishing near Providence or Newport.”

Notice that there are still three -ing words close together, but the preposition about separates the first two.

However, many examples of three -ing words together do not sound natural. Listen to this example from the website English Stack Exchange:

Some doctors are considering stopping recommending high-carb diets.

According to the website, this sentence is grammatically correct. However, it sounds less natural than the example about fishing.

Now, listen to a sentence with the same meaning.

Some doctors are rethinking recommending high-carb diets.

It sounds a little better than the original example. But this next one sounds better:

Some doctors are rethinking their recommendations of high-carb diets.

These examples sound more natural in English.

Putting three -ing words together is often complicated and can sound unusual. So, until you’ve mastered English, you should probably avoid it. However, in many situations you can feel comfortable using two -ing words in a row.