A:m(CO2):m(H2O)=44:18
B:v(C5H4) :v(CO2)=1:5
C:m(CO2):m(H2O)=55:18
D:v(C5H4) :v(CO2)=1:2
Come and visit England—museums and parks
British Museum
Subway: Tottenham Court Rd
You can get the information about Rosetta Stone inscriptions (碑文)here.
You can also take a walk in Great Court. It is the biggest indoor square in Europe.
National Library
Subway: Charing Cross
You can see more than 2000 famous paintings from the famous Europeans here.
It is one of the largest art galleries in the world.
Natural History Museum
Subway: South Kensington
You can experience the fearful time. It brings you to the terrible time of the dinosaurs.
You can see other wonders of nature here with your own eyes.
Greenwich Park
Light rails
You can see the beautiful roses here.
It is London's oldest royal(皇家的) park with the longest history. The Royal Weather Station is here, too.
如图,扇形折扇完全打开后,如果张开的角度(∠BAC)为120°,骨柄AB的长为30cm,扇面的宽度BD的长为20cm,那么这把折扇的扇面面积为( )
用计算器求243,第三个键应按( )