OG 17讨论及请教

以下是引用Venus在2003-11-5 5:57:00的发言：
2和4？
2.用排除法a 对，但我觉得应该是response to "weak " electrical stimuli, 因为tactile can also respond to electrical stimuli?

4.我读不出文章有speed 得比较？？

谢谢

Attached the article:
Australian researchers have discovered electroreceptors
(sensory organs designed to respond to electrical fields)
clustered at the tip of the spiny anteater’s snout. The
researchers made this discovery by exposing small areas of
(5) the snout to extremely weak electrical fields and recording
the transmission of resulting nervous activity to the brain.
While it is true that tactile receptors, another kind of
sensory organ on the anteater’s snout, can also respond to
electrical stimuli, such receptors do so only in response to
( 10) electrical field strengths about 1,000 times greater than
those known to excite electroreceptors.
Having discovered the electroreceptors, researchers are
now investigating how anteaters utilize such a sophisticated
sensory system. In one behavioral experiment, researchers
(15) successfully trained an anteater to distinguish between
two troughs of water, one with a weak electrical field
and the other with none. Such evidence is consistent with
researchers’ hypothesis that anteaters use electroreceptors
to detect electrical signals given off by prey; however,
( 20) researchers as yet have been unable to detect electrical
signals emanating from termite mounds, where the favorite
food of anteaters live. Still, researchers have observed
anteaters breaking into a nest of ants at an oblique angle
and quickly locating nesting chambers. This ability quickly
(25)to locate unseen prey suggests, according to the researchers, that the anteaters were using their electroreceptors
to locate the nesting chambers.