Could you provide the sentance that the question is talking about? You could youse dictionary.com to look it up and see if any of the definitions it gives you corresponds to the way the word is used
Answer is :
Oaks are usually the tallest trees
Oaks are also more “conductive” because of their higher moisture content and attract lightening
If the word is 'was', then it is a linking verb.
This is only for small q not essays or 100 words or more bro just letting u know