我目前是高二生，想知道要如何準備學測，尤其是英文，英文文法很弱，常常動詞都不知道要如何變化，非常苦惱?

Buy a grammar book.
Finite and non-finite verbs:-
He "failed" to finish his exam.work.
In this eg,"failed" is a finite verb but "to finish" (infinitive) is a non-finite verb.
Finite verbs are verbs that are limited by person, number, tense mood and voive.
Non-finite verbs include participles, gerunds and infinitives which are also called verbals.
Conjugation:-
By conjugation, we mean the inflexional system of verbs. The system divides verbs according to persons, numbers, tenses, moods and voices.
The forms of the verb eg:-"take--taking--took--taken---" in the following examples:-
I "take" some books to the school-classroom every day.
I am" taking" some bks to sc.now.
I "took" some bks to sc.yesterday.
I have" taken "some bks. to the class.
I shall "take" some exam. bks to sc. to-morrow.
There are four forms of the verb"take":-
(1)Present tense and infinitive:-take
(2)Present participle---taking
(3)Past tense:-took
(4)Past participle:-taken; eg:-I have already "taken" and read some grammar books .I shall commit them to memory,learn it all by heart.

去買賴氏英文文法書

讀完後

可以買一些多益的書
準備多益考試 1500$NTD

我也是高二^^