桔子外皮属于_________组织；桔子的果肉属于_________组织，所以在植物的结构层次中一个桔子应属于_________。
物质之间发生化学反应时，一定发生变化的是A.颜色 B.状态 C.原子核 D.化学键
小苏打（主要成分为NaHCO3）中常含有少量氯化钠．化学兴趣小组的同学为了测定某品牌小苏打中NaHCO3的质量分数．进行了以下实验：称量样品置于烧杯
在水深超过200 m的深海，光线极少，能见度极低，有一种电鳗具有特殊的适应性，能通过自身发出生物电，获取食物，威胁敌害，保护自己.若该电鳗的
Cell phones _______ by more and more teens and many new functions _______ to them nowadays. A. are using, have added B. is used, are adding C. are bein
阅读下面古诗，按要求回答问题。 冷香菊 [宋]陈荣卿 晚秋风紧晓霜严，香阵飘飘透竹帘。 荒径幽林甘冷落，肯于人世学趋炎? 1．本诗一、二两句描写
将下列句子中的汉语部分译成英语，注意使用适当的形式。 66.If you are hard-working, your dream (实现) soon. 67.Please leave here
I walked into the grocery store, not really wanting to buy anything. I just wanted to stay there quietly — the pain of losing my 11 was still too great. And this supermarket held so many
