Answer:
its
theyve
scientists
known,
size
professor
now"
Step-by-step explanation:
its
Missing apostrophe, it should be "it's"
theyve:
Missing apostrophe, it should be "they've"
scientists:
Missing apostrophe, it should be "scientists' careful"
known,
There should be no comma after this word
size
There should be a comma after this word to correctly separate two independent clauses.
professor
When the word "professor" is someone's title, like in this case, it requires a capital letter, so it should be "Professor"
now"
Since this is the end of a sentence there´s a missing period mark. It should be: now."