By Dr. Larry Malashock It is always easier, safer and less expensive to prevent a problem rather than to treat one. Most employees and their dependants have health insurance or a vision program that includes a routine eye examination. However, many of these programs offer more than that. Most of my patients with eye care benefits from their employers look at the program as insurance that gets them a yearly eye exam. They use it or not as they see fit. However, most of the “eye care” programs are not insurance programs per se but more of a material benefits program that should be used every year, too. Typical vision… More
In short, whenever the information is essential to identifying the subject, the proper pronoun to use is that. If the information is not essential, or can be set apart with commas, then the pronoun which is more likely to be correct. As is the case with English grammar rules, however, there are going to be some exceptions to this rule. When in doubt, writers can try removing the relative clause and asking themselves if the sentence sounds complete and informative. Some grammar experts suggest silently adding the words "by the way" after which to determine if the information is relevant or irrelevant. If "by the way" seems to fit, then the clause is non-restrictive and should be set off with commas.