下列关于肺动脉的叙述，哪一项是错误的（） A.三个半月形瓣，称为左、右、无冠状瓣 B

阅读理解。

     The word "day" has two meanings. When we talk about the number of days in a year, we are using "day"

to mean 24 hours. But when we talk about day and night, we are using "day" to mean the time between sunrise

and sunset. Since the earth looks like a ball, the sun can shine on only half of it at a time. Always one half of

the earth is having day and the other half night. A place is moved from day into night and from night into day

over and over by the spinning (旋转) of the earth. At the equator (赤道) day and night are sometimes the same

length (长度). They are each twelve hours long. The sun rises at 6 o'clock in the morning and sets at 6 o'clock

in the evening. For six months the North Pole is tilted (倾斜) toward the sun. In those months the Northern

Hemisphere (半球) gets more hours of sunlight than the Southern Hemisphere. Days are longer than nights.

South of the equator nights are longer than days. For the other six months the North Pole is tilted away from

the sun. Then the Southern Hemisphere gets more sunlight. Days are longer than nights. North of the equator

nights are longer than days. Winter is the season of long nights. Summer is the season of long days.

1. When the Western Hemisphere is having day, the Eastern Hemisphere is having ______. [ ]

A) both day and night

B) day

C) night

2. A place is moved from day into night and from night into day over and over by ______ of the earth. [ ]

A) the pushing

B) the pulling

C) the spinning

3. At the equator day is as long as night ______.[ ]

A) sometimes

B) never

C) usually

4. When the North Pole is tilted toward the sun, the Northern Hemisphere gets ______ sunlight. [ ]

A) less

B) more

C) all

5. When it is winter in China, ______. [ ]

A) the USA is tilted toward the sun 　

B) the South Pole is tilted away from the sun 　

C) the North Pole is tilted away from the sun

解方程：2（x+2）²=x²-4

Yukio has _____ short hair and _____ big eyes. [ ]

A. a ; a

B. / ; a

C. / ; /

D. a ; /

种群逻辑斯谛增长曲线分为哪五个时期简述各时期的种群数量变化特征。

当分部工程较大或较复杂时，可按( )等划分为若干子分部工程。

A．施工特点

B．材料种类

C．专业系统及类别

D．建筑部位

E．施工程序