@ Experts - Although I got this one correct, a quick question on the function of UNLESS . It (re 'UNLESS') means "If NOT", right ?

RBBmba@2014 wrote:A patient accusing a doctor of malpractice will find it difficult to prove damage if there is a lack of some other doctor to testify about proper medical procedures.

(A) if there is a lack of some other doctor to testify
(B) unless there will be another doctor to testify
(C) without another doctor's testimony
(D) should there be no testimony from some other doctor
(E) lacking another doctor to testify

A lack of X means NOT ENOUGH OF X.
A: a lack of some other doctor
Here, the conveyed meaning -- that there is NOT ENOUGH OF SOME OTHER DOCTOR -- is nonsensical.
Eliminate A.
.
The future tense cannot serve to express a CONDITION.
For this reason, unless + FUTURE TENSE is ALWAYS WRONG.
Generally, the verb in an unless-clause should be in the SIMPLE PRESENT TENSE.
Incorrect: John will not attend unless Mary will attend.
Correct: John will not attend unless Mary ATTENDS.

B: unless there will be another doctor
Here, will be (future) cannot serve to express the condition conveyed by the unless-clause.
Eliminate B.

E: damage lacking another doctor
Here, lacking another doctor seems to modify damage, implying that DAMAGE is LACKING ANOTHER DOCTOR.
Not the intended meaning.
Eliminate E.

A modifier should be AS CLOSE AS POSSIBLE to what it serves to modify.
C: without another doctor's testimony about proper medical procedures
D: testimony from some other doctor about proper medical procedures
C is free of errors and positions about proper medical procedures closer to its intended referent -- testimony -- than does D.
Eliminate D.

The correct answer is C.

RBBmba@2014 wrote:@ Experts - Although I got this one correct, a quick question on the function of UNLESS . It (re 'UNLESS') means "If NOT", right ?

Yes.
A patient will find it difficult to prove damage unless a doctor testifies.
Conveyed meaning:
A patient will find it difficult to prove damage if a doctor does not testify.

Asked on another forum:

TheUltimateWinner wrote:

A patient accusing a doctor of malpractice will find it difficult to prove damage if there is a lack of some other doctor to testify about proper medical procedures.

(A) if there is a lack of some other doctor to testify
(C) without another doctor’s testimony

It seems that choices A and C are same regarding meaning issue, aren't they? Could you share your thought on the basis of 'some other' and 'another' issue?

Generally, an infinitive (to + VERB) expresses an INTENDED action -- an action that is not actually happening but is only intended.
As a result, option A does not convey that testimony from some other doctor is needed.
The usage of to testify in A conveys only that testimony from some other doctor is INTENDED.
This meaning seems strange.
Common sense tells us the following:
For damage to be proven, some other doctor must do more than just INTEND to testify -- the doctor must ACTUALLY testify.

The meaning conveyed by the OA is far more logical.
OA: A patient...will find it difficult to prove damage without another doctor's testimony.
Here, the phrase in blue implies that testimony from another doctor is NEEDED -- that without the testimony, a patient will find it difficult to prove damage.

Since C conveys a more logical meaning than A, eliminate A and choose C.

More about the usage of a lack of:

Generally, a lack of must refer to a noun that can be modified by much or many.
Since it is possible to have MUCH motivation, it is possible to suffer from A LACK OF motivation.
Since it is possible to have MUCH money, it is possible suffer from A LACK OF money.
Since it is possible to have MANY friends, it is possible to suffer from A LACK OF friends.

A: a lack of some other doctor
It is not possible to have MUCH some other doctor or MANY some other doctor.
Thus, the phrase above is nonsensical.
The following would be acceptable:
a lack of OTHER DOCTORS
The referent in green is viable because it is possible to have MANY other doctors.