Allusion.
Both examples come from the Bible. The first comes from the Old Testament and the second from the New. You have to be a little knowledgeable of the Bible to catch on to either one of them (or be good with Google).
It's raining outside so she can't go to her friend's houses.
Answer:
I would think that this means that he can use his happiness to hide his true face and emotions. He can put the mask on and appear happy to others, when really he is not. This acts like a mask because a mask makes your face look like something it isn't. Like on Halloween when you dress up, wearing a mask makes you look like what you desire to look like, not what you really are.
Sentence 1: People know that taking tests is hard, but they will get better grades by studying.
Sentence 2:
I learned this lesson when my friend and I studied all afternoon, then aced our final exam in biology.
Sentence 3:
I suggest that if someone wants to do well, one should try studying, too.
Sentence 4: In my opinion, scoring well on it is all about how I prepare.
Boss up on these ninja boss up yea aye