diff --git a/strings.Rmd b/strings.Rmd
index 4a321d5..76e4b3b 100644
--- a/strings.Rmd
+++ b/strings.Rmd
@@ -366,7 +366,7 @@ str_view(x, 'C[LX]+?')
     1. `"\\{.+\\}"`
     1. `\d{4}-\d{2}-\d{2}`
     1. `"\\\\{4}"`
-    
+
 1.  Create regular expressions to find all words that:
 
     1. Start with three consonants.
@@ -378,7 +378,7 @@ str_view(x, 'C[LX]+?')
 
 ### Grouping and backreferences
 
-Earlier, you learned about parentheses as a way to disambiguate complex expressions. They also definie "groups" that you can refer to with _backreferences_, like `\1`, `\2` etc. For example, the following regular expression finds all fruits that have a repeated pair of letters.
+Earlier, you learned about parentheses as a way to disambiguate complex expressions. They also define "groups" that you can refer to with _backreferences_, like `\1`, `\2` etc. For example, the following regular expression finds all fruits that have a repeated pair of letters.
 
 ```{r}
 str_view(fruit, "(..)\\1", match = TRUE)
@@ -401,7 +401,7 @@ str_view(fruit, "(..)\\1", match = TRUE)
     1. Start and end with the same character.
     
     1. Contain a repeated pair of letters
-       (e.g. "church" contains "ch" repeated twice)
+       (e.g. "church" contains "ch" repeated twice.)
     
     1. Contain one letter repeated in at least three places
        (e.g. "eleven" contains three "e"s.)