北京的高等学校、科研机构、博物馆的数量居全国第一，这说明北京是全国的（      ）

阅读下面短文，掌握其大意，从每题所给的A、B、C、D四个选项中，选出最佳选项。
FOUND
Black wallet with some money.
Come to Room 502 in the evening, or call 9796788.
WANTED IMMEDIATELY
A boy or a girl to deliver newspapers
Pay: $ 10 per day
Hours: 3:30 a.m. to 8:30 a.m. from Mon. to Sat.
For more information
Call Mr. Jones on 8947659     Call Jeff on 3338651
SINGLES’(单身) CLUB
A club for single people looking for new friends.
Ages: 25-40
Activities: parties, swimming, concerts, dances, etc
We meet every Friday at 8:30 p.m.
28 Garden Street        Tel: 7026449    E-mail: singleclub@yahoo.com

医疗上用的生理盐水是0.9%的氯化钠溶液．要配制0.9%的氯化钠溶液100g．其中选用仪器或操作正确的是（　　）