Question

emma woke up excited because after school, she would start her volunteer job at the animal shelter. as the hour approached, she could feel her excitement intensify. she could barely keep her mind on her schoolwork. by the time the dismissal bell rang, she felt like she might burst! she could hardly wait to meet all the animals she would be helping.
the word ending -ify means “to cause to become a certain way.” using your knowledge of intense, complete the sentence with a phrase that means the same as intensify.
as the hour of her new job approached, emma could feel her excitement

Explanation:

Given that -ify means "to cause to become a certain way", and the base - word is "intense". So "intensify" means to cause to become intense.

Answer:

cause to become intense