e of+名词是固定搭配,表示be 这个名词的形容词形式
is great importance 语法错误
答案肯定是D,这个逗号表明了是非限制定语从句
逗号后的句子如果是主谓宾完整的句子必须有连词,比如and,but等等
这题就算是加了AND C选项Our chemistry teacher gave us another piece of advice,and i think which is of great importance to the experiment也是语法错误,后句“which”指代不清,一定要用,也只能是Our chemistry teacher gave us another piece of advice,and i think IT is of great importance to the experiment