Lad lygten ligge i tasken, hvis det ikke er mørkt.

Lad is the imperative form of the verb at lade.

So:

• at lade = to let / to leave
• lad! = let! / leave!

In commands, Danish uses the imperative, just like English uses leave rather than to leave.

So Lad lygten ligge ... means something like Leave the flashlight ... or more literally Let the flashlight lie ...

Because Danish often uses lade + something + infinitive in a way that corresponds to English let something stay/remain.

Here:

• Lad lygten ligge
  literally: Let the flashlight lie
• natural English: Leave the flashlight where it is

So this is not about giving permission to the flashlight. It is an idiomatic way of saying don’t move it; let it remain there.

This is a very common Danish learner question.

The difference is:

• ligge = to lie / to be lying / to be in a position
• lægge = to lay / to put / to place something somewhere

In this sentence, the idea is leave it where it already is, so Danish uses ligge.

Compare:

• Lad lygten ligge i tasken. = Leave the flashlight in the bag.
• Læg lygten i tasken. = Put the flashlight in the bag.

So lægge would mean moving it into the bag, while ligge means remaining in the bag.

After lade, Danish normally uses a bare infinitive, meaning the infinitive without at.

So:

• lade nogen gøre noget
• lade noget ligge

That is why you get:

• Lad lygten ligge not
• Lad lygten at ligge

This is similar to English let someone do something, not let someone to do something.

Because they are in the definite singular form.

In Danish, the definite article is usually attached to the end of the noun:

• en lygte = a flashlight

• lygten = the flashlight

• en taske = a bag
• tasken = the bag

So instead of a separate word like English the, Danish often adds -en or -et to the noun.

Here det is an impersonal/dummy subject, just like English it in:

• if it is dark
• if it is cold
• if it is raining

It does not refer to a specific object. It just talks about the general situation or environment.

So:

• det er mørkt = it is dark

This det works very much like English it in weather and condition expressions.

Because adjectives used after det er in this kind of expression usually appear in the neuter form.

So you get:

• det er mørkt = it is dark
• det er koldt = it is cold
• det er varmt = it is warm

The -t form is very common with impersonal det expressions.

Because this part is a subordinate clause introduced by hvis.

In Danish subordinate clauses, sentence adverbs like ikke typically come before the finite verb.

So:

• hvis det ikke er mørkt = if it is not dark

This is an important Danish word-order pattern.

A useful rule of thumb:

• in many main clauses, the finite verb comes early because of V2 word order
• in subordinate clauses, ikke often comes before the verb

This sentence is a good example of that pattern.

Here hvis means if.

So:

• hvis det ikke er mørkt = if it is not dark

In Danish, hvis can sometimes correspond to English whether, depending on the sentence, but in this example it is clearly a condition: if.

Because i means in/inside.

So:

• i tasken = in the bag

That fits the idea that the flashlight is inside the bag, not on top of it or next to it.

For comparison:

• på tasken would mean on the bag
• ved tasken could mean by/near the bag

Yes, that is possible.

You can put the if-clause first:

• Hvis det ikke er mørkt, lad lygten ligge i tasken.

You can also keep the original order:

• Lad lygten ligge i tasken, hvis det ikke er mørkt.

The original version sounds natural and keeps the command first. Putting the hvis-clause first gives more emphasis to the condition.

Not always. Lygte can refer to different kinds of lights depending on context, such as:

• flashlight
• torch
• lantern

In this sentence, flashlight is a natural translation, but the exact English word can depend on context and region. British English often prefers torch where American English uses flashlight.