“藕断丝连”中的丝属于______组织，这种组织分布在植物体的______、__

自行车尾灯能够把车后任何方向射来的光都朝着相反方向反射回去，这是因为尾灯上安装了：[ ]

A．平面镜

B．多组直角棱镜

C．多组凹面镜

D．多组凸面镜。

最可能的诊断为

A．21-三体综合征

B．高精氨酸血症

C．先天性甲状腺功能低下

D．苯丙酮尿症

E．半乳糖血症

上海证券交易所B股买卖委托，一个交易单位的标准为（）。

A、100股

B、500股

C、1000股

D、1500股

1.Secure Net (SN) manufacture security cards that restrict access to government owned buildings around the world.The standard cost for the plastic that goes into making a card is $4 per kg and each card uses 40g of plastic after an allowance for waste. In November 100,000 cards were produced and sold by SN and this was well above the budgeted sales of 60,000 cards.The actual cost of the plastic was $5·25 per kg and the production manager (who is responsible for all buying and production issues) was asked to explain the increase. He said ‘World oil price increases pushed up plastic prices by 20% compared to our budget and I also decided to use a different supplier who promised better quality and increased reliability for a slightly higher price. I know we have overspent but not all the increase in plastic prices is my fault’The actual usage of plastic per card was 35g per card and again the production manager had an explanation. He said ‘The world-wide standard size for security cards increased by 5% due to a change in the card reader technology, however, our new supplier provided much better quality of plastic and this helped to cut down on the waste.’SN operates a just in time (JIT) system and hence carries very little inventory.Required:

(a) Calculate the total material price and total material usage variances ignoring any possible planning error in the figures. (4 marks)

青鱼、草鱼、鲢、鳙夏季适应水体溶氧量为4-4.5mg/L，鲑、鳟鱼类夏季适应水体溶氧量为（）。