【单选题】On Buy Nothing Day, people are encouraged ________anything.
【单选题】有一个边长为【图片】的均匀裸立方体堆,堆内热中子通量密度为:【图片】若堆芯内的扩散系数为0.84cm,扩散长度为17.5cm,则单位时间内整个堆芯被吸收的热中子数为___________【图片】个。(结果精确到小数点后4位有效数字)
【单选题】目前关于氧化磷酸化机制的理论获得较多支持的是
【单选题】The best title for the passage might be ______.
A.
Buy Nothing Day in the U.S.
B.
The Future of Buy Nothing Day
C.
Free Dinners on Buy Nothing Day
D.
Students'Activities on Buy Nothing Day
【简答题】有一个边长为【图片】的均匀裸立方体堆,堆内热中子通量密度为【图片】。若堆芯内的扩散系数为0.84cm,扩散长度为17.5cm,则单位时间内整个堆芯内被吸收的热中子数为___________【图片】个。(结果精确到小数点后4位)
【单选题】常用的通量测定方法中,()强调根据乱流扩散理论,通过单位面积的任意动量或标量的通量密度是其浓度梯度与扩散系数的函数。
【单选题】According to the passage, which of the following statements is TRUE?
A.
Buy Nothing Day has become popular in the United States.
B.
Restaurants have a tradition of donating food on holidays.
C.
Girl shops are expected to be closed on Buy Nothing Day.
D.
Children like the idea of Buy Nothing Day best.
【单选题】Ad valorem tariffs are collected as
A.
fixed amounts of money per unit traded.
B.
a percentage of the price of the product.
C.
a percentage of the quantity of imports.
【判断题】“Ad. Val.”(Ad Valorem)又称从价运费。
【简答题】写出下列物理量的单位(无单位的必须写“无”) : 热导率 热扩散系数