Cada vez que tengo dudas con una preposición, busco un ejemplo y luego añado un adverbio sencillo.

Yes. Cada vez que is a very common Spanish expression meaning every time that or whenever.

In this sentence, it introduces a repeated situation:

• Cada vez que tengo dudas... = Whenever I have doubts...

A common mistake for English speakers is trying to say cada vez cuando, but standard Spanish uses cada vez que.

Spanish often uses the simple present where English might sometimes use a continuous form.

Here, tengo dudas means I have doubts or I’m unsure. Because the sentence describes a habitual or repeated action, the simple present is the natural choice:

• Cada vez que tengo dudas... = Whenever I have doubts...

Using estoy teniendo dudas would sound much less natural here and suggests a more temporary, right-now process in a way Spanish usually avoids in this kind of sentence.

Dudas con is natural when talking about having difficulty with something:

• Tengo dudas con una preposición = I have doubts / trouble with a preposition

You may also hear dudas sobre in some contexts, especially for questions about a topic:

• Tengo dudas sobre este tema = I have doubts/questions about this topic

Dudas de usually means doubts about whether something is true or doubt concerning someone/something:

• Tengo dudas de que sea correcto = I doubt that it’s correct

So in this sentence, con works well because the speaker is struggling with how to use a preposition.

Spanish often uses the singular after expressions like this when talking about a typical example of something.

So:

• dudas con una preposición = doubt about a preposition
• busco un ejemplo = I look for an example
• añado un adverbio sencillo = I add a simple adverb

This does not mean only one specific preposition exists. It just presents the action in a general, typical way.

Because Spanish usually drops subject pronouns when the verb ending already shows who the subject is.

Here:

• tengo
• busco
• añado

all clearly indicate I.

So yo is unnecessary unless the speaker wants emphasis or contrast:

• Yo busco un ejemplo, pero él no = I look for an example, but he doesn’t

In a neutral sentence, leaving out yo sounds more natural.

Because the sentence describes a habit or routine.

The pattern is:

• Cada vez que
  • present tense
• main clause also in present tense

So the meaning is basically:

• Whenever this happens, I do this

This is one of the most common uses of the present in Spanish: repeated or habitual actions.

In sentences about habitual actions like this one, cada vez que normally takes the indicative:

• Cada vez que tengo dudas...

That is because the action is presented as something real and repeated.

You may see a subjunctive only when the action is future or not yet realized in certain contexts, but with a sentence like this, the indicative is the normal choice.

So for this example, tengo is exactly what you would expect.

The comma separates the introductory subordinate clause from the main clause:

• Cada vez que tengo dudas con una preposición,
• busco un ejemplo y luego añado un adverbio sencillo.

This is very natural in writing, especially when the opening clause is fairly long. Spanish punctuation often uses a comma here just as English would.

Luego means then, afterwards, or next.

Here it connects the two actions in sequence:

1. busco un ejemplo
2. luego añado un adverbio sencillo

So the idea is I look for an example and then I add a simple adverb.

Its position is flexible. You could also say:

• ...y añado luego un adverbio sencillo
• ...y después añado un adverbio sencillo

But the original placement is very natural.

Both verbs can mean I add, but añadir is very common and neutral in Spain.

So:

• añado = I add

Agregar is also correct Spanish, but it is often felt to be more common in many parts of Latin America than in Spain. Since this is Spanish from Spain, añado is a very natural choice.

The key letter is ñ, which is different from n.

• añado is pronounced roughly like an-YAH-doh
• the ñ sounds like the ny in canyon

So it is not the same as anado.

This letter appears in many common Spanish words, such as:

• año = year
• niño = boy
• España = Spain

Because adjectives must agree with the noun they describe.

• adverbio is masculine singular
• so the adjective must also be masculine singular: sencillo

That is why the sentence says:

• un adverbio sencillo

If the noun were feminine, the adjective would change:

• una palabra sencilla

Yes, you could say un adverbio simple, and it would be understandable. However, sencillo often sounds a bit more natural here in the sense of easy or straightforward.

So:

• sencillo = simple, easy, uncomplicated
• simple = simple, but sometimes more neutral or technical depending on context

In this sentence, sencillo is a very good choice.

It means I look for an example or I search for an example.

The verb buscar is the normal verb for to look for:

• Busco un ejemplo = I look for / search for an example

English speakers sometimes expect a separate word for for, but in Spanish buscar already includes that idea, so you do not say buscar por in this meaning.

Not with exactly the same meaning.

• Cada vez que = every time / whenever
• cuando = when

If you say:

• Cuando tengo dudas...

it can still be understood, but cada vez que makes the repeated, habitual meaning much clearer. It emphasizes that this happens repeatedly, not just on one occasion.