story: Two boys bought a tub of popcorn at the movie theater. Every time one boy grabbed some, the other would too. They each took turns eating the popcorn. They ended up eating the same amount each. The boys got a refill on popcorn and did it again.
 selected sentence: Every time one boy grabbed some, the other would too.
The two boys share the popcorn >Causes/Enables> The two boys take turns with the popcorn