Grammar suggestions from @zhaoy

iteration.Rmd

@@ -94,7 +94,7 @@ Every for loop has three components:
 
 That's all there is to the for loop!
 Now is a good time to practice creating some basic (and not so basic) for loops using the exercises below.
-Then we'll move on some variations of the for loop that help you solve other problems that will crop up in practice.
+Then we'll move on to some variations of the for loop that help you solve other problems that will crop up in practice.
 
 ### Exercises
 
@@ -285,7 +285,7 @@ This is common when doing simulations.
 For example, you might want to loop until you get three heads in a row.
 You can't do that sort of iteration with the for loop.
 Instead, you can use a while loop.
-A while loop is simpler than for loop because it only has two components, a condition and a body:
+A while loop is simpler than a for loop because it only has two components, a condition and a body:
 
 ```{r, eval = FALSE}
 while (condition) {
@@ -724,7 +724,7 @@ Purrr provides two other useful adverbs:
 ## Mapping over multiple arguments
 
 So far we've mapped along a single input.
-But often you have multiple related inputs that you need iterate along in parallel.
+But often you have multiple related inputs that you need to iterate along in parallel.
 That's the job of the `map2()` and `pmap()` functions.
 For example, imagine you want to simulate some random normals with different means.
 You know how to do that with `map()`: