The morning had been a disaster.My tooth was aching，and I’d been in an argument with a friend.Her words still hurt：“The trouble with you is that you won’t put yourself in my place.Can’t you see things from my point of view？” I shook my head stubbornly—and felt the ache in my tooth.I’d thought I could hold out till my dentist came back from holiday，but the pain was really unbearable.I started calling the dentists in the phone book，but no one could see me immediately.Finally，at about lunchtime，I got lucky.
“If you come by right now，” the receptionist said，“the dentist will fit you in.”
I took my purse and keys and rushed to my car.But suddenly I began to doubt about the dentist.What kind of dentist would be so eager to treat someone at such short notice？Why wasn’t he as busy as the others?
In the dentist’s office，I sat down and looked around.I saw nothing but the bare walls and I became even more worried.The assistant noticed my nervousness and placed her warm hand over my icecold one.
When I told her my fears，she laughed and said，“Don’t worry.The dentist is very good.”
“How long do I have to wait for him？” I asked impatiently.
“Come on，he is coming.Just lie down and relax.And enjoy the artwork，” the assistant said.
“The artwork？” I was puzzled.
The chair went back.Suddenly I smiled.There was a beautiful picture，right where I could enjoy it：on the ceiling.How considerate the dentist was！At that moment，I began to understand what my friend meant by her words.
What a relief！ (2013·重庆，A)
小题1:Which of the following best describes the author’s feeling that morning?
A．Cheerful.
B．Nervous.
C．Satisfied.
D．Upset.小题2:What made the author begin to doubt about the dentist?
A．The dentist’s agreeing to treat her at very short notice.
B．The dentist’s being as busy as the other dentists.
C．The surroundings of the dentist’s office.
D．The laughing assistant of the dentist.小题3:Why did the author suddenly smile?
A．Because the dentist came at last.
B．Because she saw a picture on the ceiling.
C．Because she could relax in the chair.
D．Because the assistant kept comforting her.小题4:What did the author learn from her experience most probably?
A．Strike while the iron is hot.
B．Have a good word for one’s friend.
C．Put oneself in other’s shoes.
D．A friend in need is a friend indeed.
)，且其上任一点(x，y)处的切线斜率为xln(1+x2)，则f(x)=______．