A: You look sleepy. Have you been burning the midnight oil recently?
B: Yes. I've been preparing for my finals.
A: Well, you must have had adequate preparation.
B: I can't say.
burn the midnight oil
Burn the midnight oil的意思是“（学习或工作）熬夜，开夜车”。
e.g. It looks like we'll have to burn the midnight oil again tonight.
e.g. The students often burn the midnight oil before a big exam.
e.g. I was up all night burning the midnight oil.
e.g. He’s been burning the midnight oil all week.
have a preparation：准备
e.g. The teacher urged his students to have a preparation for the exam.
e.g. The teacher instructed the class to have a preparation for a test.