grammer

1. The problem was reported (past tense - passive Voice)
2. The problem has been reported.(present tense - passive Voice)

past tense & present prefect tense 分辨?
兩者都表示動作已完成(past tense 指出時間 / present prefect tense 無指出時間)
Tom did his homework (1 hour ago).
Tom has done his homework.

若成篇文章都用Past Tense, 不用次次重覆 指出時間

The problem was reported yesterday.
(passive voice+past tense)
Generally speaking, the time when the action was finished is mentioned in past tense

The problem has been reported.
(passive voice+present perfect)
The problem was reported but not specified the time / day that it was report

-The problem was reported.
This sentence is <Ｐａｓｔ　Ｔｅｎｓｅ>
Because of <ｗａｓ>

-The problem has been reported.
This sentence is <Ｐｒｅｓｅｎｔ　Ｐｅｒｆｅｃｔ　Ｔｅｎｓｅ>
Because of <ｈａｓ＋ (verb)>

The problem was reported.
呢句係用Ｐａｓｔ　Ｔｅｎｓｅ
因為係用ｗａｓ
The problem has been reported.
呢句係用Ｐｒｅｓｅｎｔ　Ｐｅｒｆｅｃｔ　Ｔｅｎｓｅ
因為係用ｈａｓ＋ (verb)