问题描述：
scientist think laser ------- one of the most useful tool in use today.
a being b. to be c. as being d be
问题解答：
我来补答
to be
think...to be...认为……是……
这句话也可以改成一个宾语从句：
Scientist think（that) laser is one of the most useful tool in use today.
再问： to be = is吗 麻烦给详细解释一下 谢谢你
再答： to be不等于is，to be是不定式，不能作谓语；is是be的一般现在时的形式，在句子中作谓语。 Scientist think laser to be one of the most useful tool in use today. Scientist think（that) laser is one of the most useful tool in use today. 上面两个句子意思相同，但结构不同。 第一句laser是宾语，to be one of the most useful tool in use today是作宾语补足语。 第二句laser is one of the most useful tool in use today是宾语从句。
