A、 So they can feel its weight.
B、 So they can examine its contents.
C、 So they can guess its age.
D、 So they can admire its beautiful color.

【正确答案】 B

【答案解析】解析：细节题。根据I’m going to pass this piece of amber around so you can see this spider trapped inside it．可知，教授让学生传看琥珀是为了让他们看清里面被困的蜘蛛。因此，正确答案为B。

A、 Tropical insects.
B、 Decayed leaves.
C、 Tree resin.
D、 Bird feathers.

【正确答案】 C

【答案解析】解析：细节题。题目问琥珀是如何形成的，根据Amber is really fossilized tree resin．可知，琥珀其实是树脂化石。因此，正确答案为C。

A、 Its amber contains numerous fossils.
B、 Its amber is the most durable.
C、 Its amber is opaque.
D、 It is the site of the oldest amber deposits.

【正确答案】 A

【答案解析】解析：细节题。根据Because it has a great many inclusions，something likes one insect inclusion for every onehundred pieces．可知，多米尼加是琥珀的重要产地，多米尼加有大量的化石，每一百片里就有一片含有昆虫的化石。inclusions的意思是“物质、夹杂物”在此联系上下文译为化石。因此，正确答案是A。

A、 Amber mined from the AppalachianMountains.
B、 Amber with no imperfections.
C、 Amber containing organic material.
D、 Amber with no inclusions.

【正确答案】 C

【答案解析】解析：推断题。题目问什么品种的琥珀对于基因研究最有价值，根据最后一句可知是能够提取DNA的。因此，正确答案是C。