Do you know Marc Yu (余俊承). He is very famous . He is only nine years old. He is a Chinese American. His mother is from Macao. He likes music very much and he has great musical talent（天赋）. He can play forty pieces of classical music now.
After hearing Mary Had a little Lamb one time at the age of three, he began playing it on the piano. Before that, he didn’t learn the piano at all. He started to take the piano lessons at the age of three. His first public performance（表演） was at the age of three , too.
Now he can play great music for people on the stage. He wants to be a famous musician like Lang Lang in the future. He likes LangLang very much. Lang Lang is his idol.
小题1:How old is Marc Yu?
A．9
B．3
C．7
D．8小题2:Where is his mother from?
A．His mother is from America
B．His mother is from Macao
C．His mother is from Tai Wang
D．His mother is from Hong Kong小题3:When did he begin to learn the piano?
A．At the age of 9
B．At the age of 5
C．At the age of 3
D．At the age of 10小题4:.How many pieces of classical music can he play now?
A．14
B．4
C．40
D．400小题5:What does Lang Lang do?
A．A pop singer
B．A rock singer
C．A musician
D．A writer
，内阻不计。理想变压器的输出端并联24只彩色小灯泡，每只灯炮均标有“6V，0.25W”，灯泡都正常发光，导线电阻不计.问:
