To make your German flow, you can link two clauses by using um...zu…, which means 'in order to'. This construction is sometimes referred to as the infinitive construction.
In the um...zu… clause, you must drop the subject and the verb in the second part of the clause, whatever its tense, and use an infinitive instead.
Here are two sentences that can easily be linked to make one fluent-sounding sentence:
Ich rufe meinen Freund an. Ich stelle ihm eine Frage. – I ring my friend. I ask him a question.
- You're going to link the two sentences together. As you already have a subject in the first sentence (ich), you can now drop the subject (ich) in the second sentence.
- Replace the verb in the second sentence - here the first person singular form stelle - with the infinitive form stellen.
- In German, the comma matters as it separates the two ideas.
Both sentences can now be linked like this:
Ich rufe meinen Freund an, um ihm ein Frage zu stellen. – I ring my friend in order to ask him a question.
Wir warten auf den Bus. Wir fahren in die Stadt. – We are waiting for the bus. We are going into town.
- Drop the subject (wir) in the second sentence.
- Replace the verb in the second sentence - here the first person plural form fahren - with the infinitive. The infinitive form fahren happens to look the same in this particular case.
- Use a comma to separate the two separate ideas.
This now gives us the following sentence:
Wir warten auf den Bus, um in die Stadt zu fahren. – We are waiting for the bus in order to go in to town.
The comma matters, as it separates the two ideas.