■AlmostとMostのほとんど
--状態
almost all scientists
almost all of the scientists

almostは副詞なのでAlmost scientistsは駄目

Almost everyone in this class can speak English.
これはOK、形容詞に見えるが副詞なので

--量
most scientists - 形容詞）全般のほとんど
most of the scientists - 代名詞）特定の中のほとんど

■Almostの使い方
--adv
She spends almost all of his money on books.
We're almost there.
That computer is almost useless.
I'm almost 30 years old.
She is almost always busy.

■Mostの使い方
--adv
You ate (the) most. あなたが一番食べた
What impressed you most?
She is most diligent. = very
FB is the most popular sport of them all.

--adj
Tom got the most points of the four. 4人の中で一番点をとった
Most children like chocolate. たいていの子供はチョコが好き

--pron =pronoun 代名詞
most of the scientists could read the book. ほとんどの科学者がその本を読むことができた

■mostにtheがつくか？副詞はtheがつかない
veryと同じとてもを意味する副詞につくmostにはtheがつかない
This medicine works most effectively.

もっともを意味する副詞のmostにはtheがつかない
My son likes Japanese food most.

多くやほとんどを意味するmostにはtheがつかない
Young people will be the ones to get most benefit from this program.
30 people were injured; most were men.

形容詞につくmostへのtheは微妙、省略可とする
This risk is (the) most likely to occur.

通常は the most + 形容詞 + 名詞
He is the most dangerous person in the world.