单项选择题

In most countries a PhD is a basic requirement for a career in academia. It is a(n) (21) to the world of independent research—a kind of intellectual (22) , created by an apprentice in close collaboration with a (n) (23) . The requirements to complete one (24) enormously between countries, universities and even (25) . Some students will first have to spend two years working on a (26) degree or diploma. Some will receive a stipend; others will (27) their own way. Some PhDs (28) only research, some require (29) and examinations and some require the student to teach undergraduates. A(n) (30) can be dozens of pages in mathematics, or many hundreds in history. As a result, newly minted PhDs can be as young as their (31) 20s or world-weary forty- (32) . One thing many PhD students have in (33) is dissatisfaction. Some describe their work (34) "slave labor". Seven-day weeks, ten-hour days, low pay and uncertain (35) are widespread. You know you are a graduate student, (36) a comment, when your office is better decorated than your home and you have a favorite flavor of (37) noodles. "It isn’t graduate school itself that is discouraging, " says one student, who confesses to rather enjoying the hunt for free pizza. "What’s discouraging is realizing the end point has been pulled out of reach. " Whining PhD students are nothing new, but there seem to be genuine problems (38) the system that produces research doctorates (the practical "professional doctorates" in fields such as law, business and medicine have a more obvious value). There is an oversupply of PhDs. Although a doctorate is (39) as training for a job in academia, the number of PhD positions is (40) to the number of job openings.

A.earlier
B.earliest
C.early
D.earliness