A:存在且有无限个
B:存在且只有有限个
C:存在且唯一
D:不存在
19世纪中期,美国北方和南方之间的矛盾主要围绕着是否成立联邦政府的问题。
动脉出血远比静脉出血要危险,这是因为动脉中的血液( )
阅读理解A
Millie:I usually ride my bike to schoo1.It takes me about twenty minutes.Sometimes,my father drives me to school in his car.
ff:My sister Mona and I like running to school.Running is good for us.Usually we leave home at half past seven.Then we get to school at seven fifty.
Alice:I don't like getting up early in the morning.So I have no time for breakfast at home.I usually have it on the school bus.I like my is ride because in the thirty minutes,I can eat my breakfast and walk with my friends.
Mike:My home is ten kilometers from my school.Every morning I
get up early.After breakfast l walk to the subway station.That
takes about ten minutes.Then I take the subway to school.It takes
twenty minutes.