新GRE小短文阅读练习题七十六

会计考友

Some regions of ocean rich in many nutrients contain very low concentrations
of iron, so relatively little plankton grows there.  Adding small amounts of iron
5 y9 F  S) k9 n0 {: n: a$ s) ito such areas of ocean soon produces a 30- to 40-fold increase in plankton.  
% H' ^3 K$ N2 BIn such amounts plankton absorbs large quantities of carbon dioxide, a gas
0 \* J  K% O( Himplicated in global warming.  Therefore an effective way of reducing global
& D% ~1 f8 o( o# S1 I5 U' y, Twarming would be to add iron to all such regions of ocean.
Which of the following, if true, provides the strongest evidence that the method
outlined, if put into effect, would not reduce global warming?
) e& R4 d; [1 x0 P; t6 s      A  Many regions of ocean that lack iron, and thus plankton, contain most of
  f; l) u+ P" g+ ]7 M" R       the same dissolved minerals as regions rich in both iron and plankton.  
6 l5 Y' t% }! W; p     B  Some regions of ocean that are already rich in iron are too poor in other
$ V2 D2 j5 u: f9 v$ B       nutrients to support significant plankton populations.  
7 A' N* ?+ O  k+ y) s    C   It would be very expensive to put into effect a program of adding iron to
: q9 s( q, u  b9 _0 r5 l# G9 _% @       all the nutrient-rich regions of ocean that lack iron.  
    D  Rapid surges in the amount of plankton in the ocean often lead to
# b, m6 j. G# h8 q8 c       increased emissions of methane, a gas also implicated in global
       warming.  
    E  In regions of ocean where there are levels of nutrients sufficient to
       support large plankton populations, the size of the population varies
7 \7 m- A8 c% B' O8 ^       with the season.  
4 N% K- ?3 G6 B% P6 C答案：D