1.主要是elect的用法.此处表示“选举”,主要指选举某人担任某职位.若所涉及的职位只有一个（即独一无二）,则通常不用冠词.如：They elected Nixon President.他们选尼克松当总统.
除以上最通常的表达外,类似以下说法也可以：
我们选他当主席.
正：We elected him (as) chairman.
正：We elected him (to be) chairman.
正：We elected him (our) chairman.
正：We elected him (as our) chairman.
有时也有用定冠词的情况（但省略该冠词更常见）.He was elected (the) President of the United States.他被选为美国总统.
但是,类似下面的句子通常要用冠词：
They elected a new president (a new mayor).他们选了一位新总统（新市长）.
第二题：前面那个复数不用多说,后面的空根据语意,岛上的动植物中的很多未被发现,是一个定语从句,而一般的much more 等词后面用that引导的从句,此处of that 省略