Answer:
1. Be thou as chaste as ice 2. as pure as snow
Step-by-step explanation:
A simile is a figurative language that aims to make the writing more colorful and interesting by using comparisons to describe an event, someone, a trait, a place, a quality, etc. And we can normally identify a simile because it has the words "like", "as" and "as in" in the sentence, as the excerpt shows.
Therefore, we can conclude that the author uses simile in these two phrases by comparing one thing to another ("chaste" to "ice", and "pure" to "snow") in order to describe how "thou" should be, and by using the word "as" when making this comparison.