What exactly is a 'trained plumber'?

[Dasha]

Test No. incompl/inter-8 "Going on foot", question 3

If you want to have your central heating checked, you need a ......... plumber.

(a) knowing
(b) trained
(c) learned
(d) careful

Test No. incompl/inter-8 "Going on foot", answer 3

If you want to have your central heating checked, you need a trained plumber.

Correct answer: (b) trained

Your answer was: incorrect
If you want to have your central heating checked, you need a knowing plumber.
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Why word -Knowing- doesn't fit in here?
Thank you Alan

[Alan]

This is used in abstract expressions like give someone a knowing (an understanding) look.
_________________
English as a Second Language
You can read my ESL story Present Simple

[kelly]

Hi Alan:
Can u explain me the whole meaning of the sentence?

Thanks in advance for your generosity

[kelly]

Hi Alan:
Can u explain me the whole meaning of the sentence?
If you want to have your central heating checked, you need a ......... plumber.

(a) knowing
(b) trained
(c) learned
(d) careful

Thanks in advance for your generosity

[Alan]

Hi Kelly,

The sentence means if you want your central heating to be examined you need to have someone look at it who is a plumber who has qualifications to show that he has had training.

Alan
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English as a Foreign Language
You can read my EFL story Progressive Forms

[Zbyněk]

How we do know he is not careful?

[Avec2012]

what's the difference of learned? Seems it's also OK as it means highly educated; having extensive information or understanding.

[Beeesneees]

[Beeesneees]

[Alan]

Hi,

'Learned' as an adjective pronounced as two syllables suggests that you are well read and with an academic background.

Alan
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English as a Second Language
You can read my ESL story Passive Voice