So far, we have worked with compound subjects whose individual parts are either singular or plural Almost all English grammar rules have exceptions that can create endless confusion for our students. That`s why, whenever an exception appears during class, I like to indicate it to refresh my students` memories. A common source of confusion is subject-verb concordance, especially when it comes to non-counting topics that end on -s. Some of these names are common in speech and writing, and you can bet they often appear on tests like the TOEIC. Here are some of the worst culprits: 3. Use an apostrophe followed by “s” (s) to show that a singular noun belongs to someone or something. Here too, the proper name Les always ends with “s”. Note that the apostrophe is added after point 2.