In our daily speech and in rough drafts, we tend to rely heavily on the various forms of the verb to be.
The verb to be is unlike any other verb because it is inert–that is, it doesn’t show any action. For example, in the sentence “The researcher is a professor at Duke” the verb is merely connects the subject with what grammarians call the subject complement. We could just as easily say “The professor at Duke is a researcher” without changing the meaning of the sentence.
It would be nearly impossible to draft documents without some linking verbs. Because you diminish the vigor of a document by using an excessive number of is and are constructions, you should try to limit their frequency. Finally, note that the progressive form of a linking verb—which involves using to be as an auxiliary verb with a participle–is much more acceptable. The advantage of the progressive form is that it illustrates action progressing over time, enabling us to shape concise sentences that indicate something is currently happening: “The coauthors are disagreeing about the order in which their names should be listed when the book is published.”
It is and there are constructions often lead to sluggish, passive sentences, so you should limit their frequency, as illustrated below.
Sample: While it is crucial for us to speak out on behalf of education, it is important that we do so in a manner consistent with statute and administrative rules.
Revision: We need to speak out on behalf of education while observing statute and administrative rules.
Sample: According to the certification theory, there is no intrinsic relation between creativity and IQ.
Revision: Certification theory posits no intrinsic relation between creativity and IQ.
However, some it is and there are constructions allow you to be more succinct and avoid repetition of a subject rather than placing the true subject at the beginning of the sentence, so you should not attempt to eliminate all such constructions.