植物体内运输有机物的结构是
A．筛管
B．导管
C．形成层
D．木质部
答案：A
题目分析：植物体有两种输导管道--导管与筛管．导管：导管的主要功能是运输水和无机盐．导管细胞的原生质体和横壁消失，纵壁增厚并木质化，是死细胞。筛管：筛管的主要功能是运输有机物质．组成筛管的细胞壁较薄，含有原生质体，细胞核消失，是活细胞．上、下细胞间的横壁上有许多小孔，称为筛孔．具有筛孔的细胞壁称为筛板．筛管细胞的原生质通过筛孔相连，成为有机物运输的通道。A、筛管的主要功能是运输有机物质，A正确；B、导管的主要功能是运输水和无机盐，B错误；C、形成层细胞可以分裂增生，向内产生木质部，向外产生韧皮部，使茎不断的加粗，C错误；D、木质部内有木纤维和导管．导管可以运输水分和无机盐，木纤维起支持作用，D错误。故选：A．
Driving Offence Points System What is Driving Offence Points System? After the introduction of this system, certain traffic offences will earn the driver points besides other punishment. If a driver makes any of these offences, the points will be recorded. When the driver gets a certain number of points, he will be forbidden to drive for a certain amount of time. What are the purposes of this system? This is a system designed to make road much safer. It can improve standards of driving and reduce the accident rates. Which traffic offences will result in Driving Offence points? Of course, not all traffic offences are covered by this system. Only those that have direct effect on road safety are included. There are altogether fourteen items.
If you have got 10 points or above, but still less 15 points, you will receive a warning letter from the Transport Department. This letter will tell your record of Driving Offence Points and remind you of the result of getting more points. It is hoped that this warning will change your driving behavior for the better. What will happen if you have got 15 points? If you have got 15 points or more within two years, a court will take away your driving license. The first time you are found guilty you will not be able to drive for three months, but if you are caught a second time you will not be able to drive for six months. 小题1:The underlined word “Offence”（paragraph 1）refers to ________.
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