the following figure shows charles darwin's finches. by now, you must have already realized how a particular structure in an organism is related to its fucntion and how this process results in an evaluation.

often a noun phrase is just a noun or a pronoun:

people like to have money.

i am tired.

it is getting late.

the present continuous is a verb tense which is mainly used to indicates that an action is in progress at the moment of speaking.  

it is formed using: person + verb to be (am/is/are) +verb + - ing form  

example: i am studying at this moment .

in addition, the present continuous is also used in order to express things that will or will not happen in the near future.

example: i am having dinner with some friends tonight.

the speaker sometimes   uses it   to express that an action is repeated and it causes irritation on the part of the speaker

example: my sister is constantly complaining about everything.

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