五大句型問題，求解!!! 1.Students use various way to hightlime the important parts in the textbook. 是S+V+O+O嗎?

Students use various way to highlight the important parts in the textbook.
＝Students use various way in order to highlight the important parts in the textbook.
全句的結構是：S+V+O
不定詞片語to highlight ...是修飾述部use various way的「修飾語」，屬副詞性質，表示「目的」。
use不是「授與動詞」，不會有兩個受詞。

Strictly speaking, the structure of the sentence is S + V + O

S (subject) = Students (noun)
V (verb) = use (transitive verb taking an object)
O (object) = way (noun)

"to highlight the important parts in the textbook" is an Infinitive Phrase functioning as adjective to modify the noun "way".

You may say the whole noun phrase "various way to highlight the important parts in the textbook" is the "object" of the sentence.

I don't agree with Louis that the infinitive phrase here is adverbial (屬副詞性質). I agree with Duncan that it should be adjectival.

different ways to do something = different ways of doing something
"to do something" (infinitive phrase) and "of doing something" (prepositional phrase) are both adjectival describing "ways".

He uses the pencil to highlight the important parts in the textbook.
(In this sentence, the infinitive phrase is adverbial, describing the purpose of using a pencil.)