A large number of tests has (or have?) been conducted.

What should it be?
Regards
NSP
A large number of tests has (or have?) been conducted. What should it be?

Both are possible. The use of "have" is in my opinion a bit informal. It would also depend on whether the emphasis is on "number" or "tests".

Regards, Einde O'Callaghan
A large number of tests has (or have?) been conducted. What should it be? Regards NSP

This is really a tricky one. I am eager to know the rule of grammar that governs such sentence construction. I feel it should be 'has' because it is 'A large number'.. and may be 'have' because of 'tests'.. not clear??? can anybody help?
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A large number of tests has (or have?) been conducted. What should it be? Regards NSP

This is really a tricky one. I am eager to know the rule of grammar that governs such sentence construction. I feel it should be 'has' because it is 'A large number'.. and may be 'have' because of 'tests'.. not clear??? can anybody help?

Both are possible, depending on whether the emphasis is on "number" or on "tests".
Regards, Einde O'Callaghan
P.S. I think I answered this question - or a similar one - recently either here or in another newsgroup.
not that critical BUT:
simple-look at the use of the object(s) in the rest of the sentence if the use is about the whole then singular
if use is about many individual parts of the group then plural

in this case what has been conducted? -tests.
i.e. all of the individual tests HAVE been done and the discussion may go on to say the RESULT IS ...
or the RESULTS ARE..
so use plural verb have
each member of the group is voting
all members of the group are voting.
the group (as a result or as a whole ) has decided (also because it is not possible for an individual to decide for the group-the decision is an aggregate )
[nq:1]A large number of tests has (or have?) been conducted. What should it be? Regards NSP
rewrite it...
"Many tests have been conducted."
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[nq:2]A large number of tests has (or have?) been conducted. What should it be? Regards NSP
This is really a tricky one. I am eager to know the rule of grammar that governs such sentence construction. I feel it should be 'has' because it is 'A large number'.. and may be 'have' because of 'tests'.. not clear??? can anybody help?

it's not tricky at all.
it's just badly written.
it should read, "Many test have been conducted."
or
"3712 tests have been conducted."
or
"Hundreds of tests have been conducted."
etc.