( )It __ that robots will replace most workers in the near future.(1)is believed (2)believe(3)be believing(4)have believed?

To Ah Sing:-
(1)It is believed-the fact,the passive voice;
------use "it" before certain nouns, adjective, and verbs to introduce point of view about a situation as Subject.;
-----"that robots-----"a noun clause, object to "It is believed"
------is better than
------many people believe=who is those people ?

(2)believe(s)-------third person singular adds an "s"

(3)(will) be believing;------present participle

(4)(has) have believed.-----present perfect tense

(1)

It is believed that robots will replace most workers in the near future.
這裡的it是虛主詞，後面的名詞子句that robots will replace most workers in the near future是延遲的主詞(delayed subject)。使用虛主詞是為避免句子頭重腳輕，將長的文字移到句尾，會較自然。

Many people believe that robots will replace most workers in the near future.
因為事情的真實性比誰相信來得重要，所以改用被動詞會比按上面的這個方式較能突顯重點是「事件」而非「人物」。