OG12 CR59 急求高人解答~

calvinmonkey

59.   In order to withstand tidal currents,juvenile horseshoe crabs frequently burrow in the sand. Such burrowing discourages barnacles from clinging to their shells. When fully grown, however,the crabs can readily withstand tidal currents without burrowing, and thus they aquire substantial populations of barnacles. Surprisingly,in areas where tidal currents are very weak,juvenile horseshoe crabs are found not to have significant barnacle populations, even though they seldom burrow.

A. Tidal currents do not themselves dislodge barnacles from the shells of horseshoe crabs.

B. Barnacles most readily attach themselves to horseshoe crabs in aeras where tidal currents are weakest.

C. The strength of the tidal currents in a given location varies widely over the course of a day.

D. A very large barnacle population can significantly decrease the ability of a horseshoe crab to find food.

E. Until they are fully grown,horseshoe crabs shed sheir shells and grow new several times a year.

答案是 E。答案我觉得和原文的关系不大啊。我不是很理解文章内容和选项。


请各位大牛帮我解释下原文和选项吧~拜托了~

weidehou

原文的意思好像是：为了抵挡潮流，年轻的马蹄蟹经常在沙滩上挖地洞。这样挖地洞可以防止barnacles 藤壶(好像是一种甲壳动物）附着在他们
（马蹄蟹）的壳上。然而，当马蹄蟹完全长大后，他们不用挖地洞就能轻而易举的抵挡潮流，这样马蹄蟹就获得大量的barnacles 附着在他们的壳
上。 另人惊讶的是，在潮流比较弱的地方，年经的马蹄蟹被发现没有大量的barnacles 附着在他们的壳上，尽管他们很少去挖地洞。
题目是让解释后面这一发现的原因。也就是在那些潮流弱的地方，为什么那些年轻的马蹄蟹不挖洞也能防止 barnacles的大量附着？？？
E选项意思是，在马蹄蟹完全长大之前，他们每年都将脱掉他们旧的壳然后长出新的壳好几次。
因为年轻马蹄蟹不断的换壳，这样附着在壳上的barnacles也就没有，这就给出了后一发现的原因。

cclovelife

upstair is great . the concise mainline is that juvenile (to withstand,burrow--> not barnacle) and grown(enable to withstand,not burrow-->barnacles ) exist,but  some juvenile in weak current area (not burrow,not barnacle). why ?

calvinmonkey

灰常感谢~~~

henguc

谢谢上面解释，
但是又有疑问，根据E的说法，那些fully grown的horseshoe crabs 的壳不是一样会 have significant barnacle populations吗？

Ferris1992

When fully grown, however,the crabs can readily withstand tidal currents without burrowing, and thus they aquire substantial populations of barnacles.
E. Until they are fully grown,horseshoe crabs shed sheir shells and grow new several times a year.

bontakuner

我也是跑来想问这题 觉得没什么联系=。=结果看见有人在问~上边高人好严密 果然应该注意一些形容词的描述