语法问题，thx

未知数325208

1, ______ they sometimes swim alone, dolphins usually congragte in large groups, often numbering in the hundreds.

A  Why    B Although   C  Even   D  Nevertheless.

我的答案是D，我觉得也解释的清除啊。  但是正确答案是 B。为什么啊？？


2, The development of synthetic fibers after 1940 led to the production of new types of fabrics _____ more durable and easier to care for.


A that they were      B   that were       C   were    D and were


为什么是B？？？


3， Today ______ little fossil  ivory remains comes from Alaska.


A  what      B  which      C  there  is         D  where  

C也可以啊，但是答案是A。

funny_1215

1 没有见过nevertheless后加从句

2 选C 或D就有两个谓语了，A中，因为That就是是指new types of fabrics ，有they就主语重复了

3选C就谓语重复了，comes from 是谓语