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Hello
I'd like to ask about "tense."

Would you help me to choose past or present perfect?
I wonder if I can choose both past and present perfect in these sentences and they can convey the same meaning or not.

Would you take a look at the following sentences?

Pattern 1
#1 It is unbelievable that he passed the examination.
#2 It is unbelievable that he has passed the examination.

Pattern 2
#3 It is clear that he broke the vase.
#4 It is clear that he has broken the vase.

Thank you.
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All four are correct and the elements of each pair convey nearly the same thing. The first and third make the actions more remote and detached from present concerns; the second and fourth make the actions more relevant to the present.

CJ
Comments  
#1 It is unbelievable that he passed the examination.
#2 It is unbelievable that he has passed the examination.

Pattern 2
#3 It is clear that he broke the vase.
#4 It is clear that he has broken the vase.

I am not sure whether both options would be 'correct,' however I think that #1 and #3 are the most easily understood ( and my best guess is that they are correct where the others might not be). I'm not too helpful, am I? Nor am I an English professor. Hah.
 CalifJim's reply was promoted to an answer.