I need help peleeease rn!

Mistakes:

its theyve scientists known, size professor now"

Explanation:

There´s a missing apostrophe, the correct grammar is "it's" There´s a missing apostrophe between "they" and "ve" There´s a missing apostrophe after the word "scientists"  There should be no comma after the word "known" There should be a comma after the word "size" to separate the two clauses.  The word "professor" requires a capital letter.There should be a period mark after the word "now"