Câu văn đụt lổ GRE

The last 3 are totally without merit, so you must choose between A and B. I know nothing about inertial guidance systems, but if I were looking for advantages, I would say that reliability and automaticity are both good choices, so the question comes down to whether "ad***ional" or "external" is the correct choice. My guess is that it is "external", because that means the system is not only automatic, but it is fully self-contained. Choosing "ad***ional" seems incorrect to me because it is not semantically logical because we don't know what "ad***ional" data might mean here beyond external.
My choice of B is just a guess, though. Please let me know what the book says is correct

Yeah, you're right! Yes, the answer is B. Try the last Q.4,5,6,7. The Q.4 is really easy!
NOW OR NEVER
Kintaro (online from Mon to Wed)

Q4. Hong Kong prospered as the center of trade with China, ______until it fell to the Japanese in 1941
(A) increasing
(B) succeeding
(C) languishing
(D) retreating
(E) burgeoning
---------------------------------------------------------------------------------------
Q5. One aim of educational technology should be to _____ instruction more precisely to the individual needs of students, because vast differences in the ways students learn are _____ when they are taught the same thing
(A) adapt..discovered
(B) direct..reinforced
(C) design..acknowledged
(D) adjust..overlooked
(E) retrofit..undermined
---------------------------------------------------------------------------------------
Q6. Proponents of urban development oppose the popular notion that social-psychological mechanisms leading to criminal and other antisocial activity are more likely to _____ if ______ such as population density, ethnic heterogeneity, and anonymity are found.
(A) function..cities
(B) react..factors
(C) disappear..problems
(D) fail..criminals
(E) emerge..traits
--------------------------------------------------------------------------------------
Q7. The science of astronomy is widely viewed today as _____ at least as much as theoretical, in that sooner or later what astronomers detect finds its way into theory, or the theory is modified to _____ it.
(A) observation..disprove
(B) beneficial..accept
(C) empirical..embrace
(D) practical..demonstrate
(E) important..supersede
---------------------------------------------------------------------------------------
My stomachache is killing me. Maybe I will go to the hospital tomorrow...
NOW OR NEVER
Kintaro (online from Mon to Wed)