Everyone knows that verbs are used to indicate actions. And to express the speaker’s attitude to action, modal verbs exist. The German language in this aspect is no different from other European languages. Whether we can, whether we want, we can, or are forced to do something - in such cases we use a modal verb in combination with an infinitive.
Example:
Du sollst leben. You must live.
Ich kann Tennis spielen. I can play tennis.
Modal Verbs in German
Können, möchten, dürfen, müssen, sollen, wollen - all of them express the desire, possibility or necessity of the action, are close in meaning, but differ in its shades.
For better memorization, modal verbs are usually divided into pairs: können and dürfen (to be able), sollen and müssen (to be proper), wollen and möchten (to want).
If the verb können means that someone has the ability or ability to do something, then dürfen is used in the sense of "have permission":
Ich kann schwimmen. I can (can) swim. In the meaning: "because I have such a skill."
Ich darf schwimmen. I can (have the ability) to swim. In the meaning: "because I am allowed to do this."
The modal verbs sollen and müssen both express obligation. What are the shades of meaning?
If the verb sollen is used in the sense of “obligated by someone’s order or instruction,” then müssen is a less categorical form of obligation (assuming awareness of one’s own need or the need to obey objective circumstances).
Wir sollen das Auto hier lassen. We must leave a car here. For example, in a situation where a traffic sign prohibits driving further, and we must walk the rest of the way.
Ich muss das Auto hier lassen. I must (forced) to leave the car here. For example, because it requires repair, and I understand that it is dangerous to continue to ride on it.
The modal verbs wollen and möchten express a desire.
But if wollen is a categorical form indicating firm intentions and already approved decisions (the implementation of which is not in doubt), then möchten is more suitable for expressing a delicate, unobtrusive request or assuming that the desired will be fulfilled. Compare:
Ich will trinken. I'm thirsty.
Ich möchte Apfelsaft trinken. I would like to drink apple juice.
As can be seen from the examples, modal verbs require additions in the form of an infinitive that is used without zu.
Du darfst nicht rauchen. You are not allowed to smoke.
Hier dürfen Kinder spielen. Children are allowed to play here.
Modal verbs vary in numbers and gender (conjugate) by adding appropriate endings and sometimes require a change in the root vowel.
For instance:
1l., Unit h.: ich darf - I can, I am allowed.
2l., Unit: du darfst - you can, you are allowed.
3l., Unit: er, sie, es darf - he, she, it can; him, her, he is allowed.
1l., Plural h.: wir dürfen - we can, we are allowed.
2l., Plural: ihr dürft - you can, you are allowed.
3l., Plural: sie dürfen - they can, they are allowed.
Polite form of contact: Sie dürfen - you can, you are allowed.
The modal verb gives an additional shade of meaning to the main verb, specifying it. Here is an example:
Lena fährt übers Wochenende nach Moskau.
Lena goes to Moscow on the weekend.
The sentence uses the main verb "fahren" - "go". And from the foregoing, we understand that Lena will not be at home on the weekend, she will leave for Moscow.
Otherwise we can say:
Lena kann übers Wochenende nach Moskau fahren.
Lena can go to Moscow at the weekend.
Using the modal verb können, we focus the reader's attention on the fact that Lena, if she wishes and favorable circumstances, can leave for Moscow - there are no obvious obstacles to this action.
Let's see what happens with the meaning of the sentence if we add the modal verb möchten:
Lena möchte übers Wochenende nach Moskau fahren.
Lena would like to go to Moscow on the weekend.
It becomes clear that Lena wants to go to Moscow, but it is not yet known whether her wish will come true.
How does the meaning of the sentence change if we use the modal verb sollen:
Lena soll übers Wochenende nach Moskau fahren.
Having read such a proposal, we know for sure that Lena must go to Moscow on the weekend, whether she wants it or not.
If the sentence uses the modal verb dürfen, then the reader will understand that Lena received permission to travel to Moscow:
Lena darf übers Wochenende nach Moskau fahren. Lena can go to Moscow with a good conscience at the weekend; apparently, her parents or other persons authoritative for her gave their consent to this trip.