下列关于植物细胞的叙述，正确的是（ ）
A．所有的植物细胞都有大液泡
B．植物细胞都是长方形
C．植物体都是由细胞构成的
D．液泡中的细胞液不含水分
A、液泡是植物细胞质中的泡状结构．幼小的植物细胞（分生组织细胞），具有许多小而分散的液泡，在电子显微镜下才能看到．以后随着细胞的生长，液泡也长大，互相并合，液泡数目越来越少，最后在成熟的细胞中央形成一个大的中央液泡，它可占据细胞体积的90%以上．故该项不符合题意；
B、植物的形态各异，不一定都是长方形，故该项不符合题意；
C、细胞学说认为：除病毒外，生物体都是由细胞构成的，细胞是生物体结构和功能的基本单位．因而植物细胞也是构成植物体结构和功能的单位．故该项符合题意；
D、液泡中的细胞液的主要成分是水，溶解着多种物质．故该项不符合题意．
故选：C．
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| My name is Wang Kun and my sister is Wang Wei. Since middle school, we have dreamed about taking agreat trip by 1 . When we graduated from college,we finally got the 2 to do it. We started our long bike ride 3 the Mekong River (循公河) in October. 4 it was autumn, thesnow had already started to fall in Tibet. Our legs felt so heavy and 5 that we thought they were ice. Have you ever seen 6 ride bicycles? Wang Wei was in front of me as usual. I knew I didn't need toencourage 7 . To climb up the mountain road was hard work but to go 8 the hills was great fun. When we reached a valley (山谷), it became much warmer. We had to 9 our clothes. In the early evening, we stopped to 10 our tents and then we ate. After supper, Wang Wei went to 11 but I stayed awake. At midnight, the sky became clear and the stars were 12 . There was almost no 13 only the sound of the fire. What a 14 night! We have already traveled so far. We are reaching Dali in Yunnan Province. There our cousins Dao Wei and Yu Hang will 15 us in the ride trip. I'm sure we'll have a greater time together. | ||||
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