Eiken må skiftes.

Because Norwegian usually puts the definite article on the end of the noun instead of using a separate word like English the.

So -en here marks definite singular: the ...

In other words, eiken means the [noun], not just the basic noun by itself.

It is singular.

For many learners, -en can look like it might be some kind of plural ending, but here it is not. In this sentence, -en is the definite singular ending.

Må is a modal verb meaning must or has to.

It expresses necessity:

• jeg må = I must / I have to
• du må = you must / you have to
• eiken må = the ... must / has to

A useful thing to notice is that må does not change for person or number the way English sometimes does.

Because skiftes is passive.

• skifte = change / replace something
• skiftes = be changed / be replaced

So the sentence is not saying that eiken does the replacing. It says that eiken is the thing that needs to be replaced.

That -s ending is a common way to form the passive in Norwegian.

After modal verbs such as kan, skal, vil, and må, Norwegian normally uses the next verb without å.

So you say:

• må skiftes

not:

• må å skiftes

This is similar to English, where we say must go, not must to go.

Yes, it is.

The structure shows that the noun is receiving the action, not doing it. The sentence focuses on what needs to happen to the thing, while leaving out who will do it.

That is very common in Norwegian, just as in English:

• The door must be closed
• The tire must be changed
• Eiken må skiftes

Yes. That is also possible.

Norwegian has two common ways to express the passive here:

• må skiftes
• må bli skiftet

They are often very close in meaning. The -s passive is shorter and very common in written and neutral language. The bli + past participle version can sound a little more explicit.

So both can work, depending on style and context.

The order is:

• Eiken = subject
• må = finite verb
• skiftes = main verb

This follows a very normal Norwegian main-clause pattern: the finite verb comes early, typically in second position.

So the sentence is built in a straightforward way: Subject + finite verb + main verb

Grammatically, må is a present-tense form, but the meaning often points to something that needs to happen now or in the future.

So Eiken må skiftes means there is a present necessity: the replacing needs to happen.

This is much like English must be replaced, which also often refers to a needed future action.

Because the speaker does not need to mention the doer.

In passive sentences, the action itself is often more important than the person doing it. If the doer is obvious, unknown, or unimportant, Norwegian often leaves it out.

So Eiken må skiftes naturally means: the important point is that it needs replacing, not who will do the replacing.