distinguish

[mengta]

Can you distinguish which plants are poisonous?
Can you distinguish the plants which are poisonous?

which sentence is correct?
thanks

[MehmetBaskan]

The second sentence is correct.

[Casiopea]

Welcome.

Could you tell us why you feel the second is correct and the first incorrect?

[trustM]

Can "distinguish" be followed by a WH-word?
Can you distinguish which plants are poisonous?-is this possible to say?
I don't feel anything wrong with either of the sentences, I feel a slight difference in meaning, but I'm probably wrong

[MehmetBaskan]

Originally Posted by Casiopea

Welcome.

Could you tell us why you feel the second is correct and the first incorrect?

We can not use two question forms in one sentence .
Please reply.I need feedback.Thank you!

[atoom]

i think both sentences are right in terms of grammar.
but there are different meanings between them.
the 1st. some plants are poisonous, but some are not. the asker wants the answerer to point out the poisonous ones.
as to the 2nd. all the plants are poisonous, the asker just wants the answerer tell him what kind of poison is every plant with.

am i right?

many thanks

[Casiopea]

Originally Posted by MehmetBaskan

We can not use two question forms in one sentence .
Please reply.I need feedback.Thank you!

Well, I believe it's about adjectives. For example,

Some of the plants are poisonous.
[1] Do you know which of the plants are poisonous?
[2] Do you know the plants that are poisonous? ~ the poisonous plants?

'which of' functions as an adjective phrase, and it takes 'the plants are poisonous' as its object. Look what happens when we take out the phrase 'which of',

which of the plants are poisonous
________the plants are poisonous
the plants that are poisonous

The clause the plants are poisonous turns into a noun + adjective clause structure:

the plants + that are poisonous (Note, which is also possible, but rare)

We can even modify the noun phrase again, by placing the adjective 'poisonous' before the noun, like this, 'the poisonous plants'.

Getting back to the poster's original two; I find both [A] and [B] acceptable:

[A] Can you distinguish which plants are poisonous (and which plants are not poisonous)?

[B] Can you distinguish the plants which are poisonous (from the plants which are not poisonous)?

Now, the oddity we pick up in [B] isn't the phrasing; it's the use of which. That is, we expect to read or hear the relative defining pronoun that, and not which. Watch this: Change the relative pronoun which to that and sentence [B] reads likes [C],

[B] Can you distinguish the plants which are poisonous (from the plants which are not poisonous)?

[C] Can you distinguish the plants that are poisonous (from the plants that are not poisonous)?

Now change the relative clause that are poisonous to an attributive adjective structure - shown in [D] - and [C] reads like [D],

[D] Can you distinguish the poisonous plants (from the non-poisonous plants)?

Does that help?

[MehmetBaskan]

Thank you very much.
I'm much obliged.

[Casiopea]

You're most welcome.

It's nice that you're around.