英文問題?

首先, "He is called Tom"同"He is calling Tom"完會係唔同意思
"He is called Tom"係用左被動式, 直接譯返做中文係「他被稱為Tom」, "He"同"Tom"係指同一個人；
"He is calling Tom"係現在進行式, 直接譯返做中文係「他正在喊叫Tom」, 係形容緊"He"現在呢一刻喊叫緊"Tom", "He"係另有其人, 可能係Peter, Tony etc., 我地唔清楚, 但"He"就一定唔係句子中所講0既位"Tom"；
"He calls Tom"係現在式, 直接譯返做中文係「他喊叫Tom」；
"He is Tom"中文譯做「他是Tom」, 係講緊一個事實(fact), 所以呢個都係現在式。

was/were+(v)+ed 係過去被動式(past passive voice)
is/am/are+(v)+ed 係現在被動式(present passive voice)
was/were+(v)+ing 係過去進行式(past continuous tense)
had+pp 係過去完成式(past perfect tense)

Simple Present Tense:

He is Tom.
(Explanation: 他是Tom)

Passive Tenses (is/am/are+(v)+ed / was/were+(v)+ed)

are used whe the subject of a clause is the person or thing affected by an action. Passive tenses are formed by using an appropriate tense of "be" and the past participle of the main verb.

He is called Tom.(他就是叫Tom，強調的是被叫做Tom) 兩句句子強調的部份是不一樣。

Another example: It is boiled before use. / My advice is being ignored. / You have been warned. / He was murdered. / We were being watched.

He calls Tom is not grammatical. You can say "He calls himself Tom".

has/have/had+pp是 perfect tense.
Perfect tenses are used when relating an action or situation to the present or to a moment in the past.

Example: Football has become international.
Before Mary called her mother, she had gone shopping on her own.
Where have you been? I have been looking for you everywhere.

is/am/are/was/were+(v)+ing 是 continuous tense

Continuous tenses are used when talking about temporary situations at a particular point in time.

Example: What are you doing now?
Mary has been talking on the phone for an hour already.
Yesterday while I was taking a shower, my brother was watching TV.

Why 'He is called Tom.' rather than 'He is calling Tom'
>'He is called Tom 他名叫Tom (被人叫) ; 'He is calling Tom'他正在叫/致電Tom
所以要視乎你想要的意思是什麼.
'He is calling Tom.' or 'He calls Tom.' or 'He is Tom.'sentence structure是對的,但不知否你要的意思.
was/were+(v)+ed : simple past passive voice
had+pp: past participle/ past perfect
is/am/are+(v)+ed: simple present passive voice
was/were+(v)+ing: past continuous