A pioneering head teacher is calling for all high schools to follow his lead and start classes at 11 am，allowing teenagers two hours extra in bed.

Dr. Paul Kelley，head of Monkseaton Community High School in North Tyneside，said it would mean the end of sleeping in lessons before lunch，after experiments showed teenagers could have different body clocks from adults and younger children.
Russell Foster，an Oxford professor of neuroscience(神经系统科学)，tested the memory of 200 Monkseaton pupils at 9 am and 2 pm using pairs of words，and discovered a 9% improvement in the afternoon. Students correctly identified 51% of word pairs in the later session，compared with 42% in the morning. Tayler McCullough,15，one of the test subjects，said the majority of students would welcome the extra hours in bed.“I'm extremely hard to get up in the morning. One or two people like to get to school early，but most of us would be up for going in later. I'm sure it would make a big difference to our learning ability.”
Kelley is adamant that a change of school timetable will have a meaningful effect on exam performance. He wants his school's governors to approve his plan and put the new timetable in place before the opening of Monkseaton's new school building，the most technologically advanced in the country，in September.
Kelley hopes his latest idea will be just as successful.“We have to be practical. But this proves that，by starting later，children's learning improves，as does their health.”
Foster said，“This is preliminary(初步的) data，but what's exciting is that it matches more detailed studies carried out in Canada and the US. Teenagers get up late not because they are lazy but because they are biologically programmed to do so.”
How many professors are mentioned in the passage?

A．One.

B．Two.

C．Three.

D．Four.

According to Russell Foster's research，________.

A．the students tested had very good memories

B．the students tested did better jobs in the afternoon

C．42% of the students tested could do very good jobs

D．51% of the students tested could master 9% of words

What does the underlined word “adamant” in the fourth paragraph mean?

A．Angry.

B．Absorbed.

C．Adaptable.

D．Determined.

Foster's opinion on teenagers' getting up late is that ________.

A．teenagers are practical

B．teenagers are lazybones

C．it's based on their body development

D．it's good for their learning and health