核冠属于 A．嵌体 B．部分冠 C．全冠 D．桩冠 E．CAD-CAM修复体

A professor of environmental health and his students began studying the idea of rooftop gardening for cities. “I think vertical farming is an idea that can work in a big way,” said Despommier.

Why would we want to build skyscrapers filled with vegetables when we’ve been farming on the ground for 10,000 years? Because as the world’s population grows—from 7 billion now to as much as 9 billion by 2050—we could run out of productive soil and water. Most of the population growth will occur in cities that can’t easily feed themselves. And the fact is that modern agriculture as well as everything associated with it – chemical fertilizers and transportation full of carbon—is a significant contributor to climate change, and suddenly vertical farming doesn’t seem so magic in the sky.

“Vertical farming could allow food to be grown locally and sustainably,” says Glen Kertz, CEO of Valcent. The result saves space — vital in urban areas — and allows farmers to irrigate and fertilize with far less waste.

At Valcent’s El Paso lab, crops grow in rows on conveyor belts. Moving them gives the plants the precise amount of light and nutrients needed, letting them grow 15 times as much vegetable as on a normal farm with 5% of the water that traditional agriculture does.

Despommier plans to build a 30-story, city-block-size vertical farm that would have transparent walls to maximize sunlight and would produce enough food for 50, 000 people. But it would cost hundreds of millions to build a full-scale skyscraper farm. That’s the main drawback: construction and energy costs would probably make vertically raised food more costly than traditional crops.

一种产品的价值由其质量与价格之间的比率决定。一种产品的价值越高，其竞争性就越强，所以对于既定产品而言，或者通过提高质量，或者通过降低价格，都会提高消费者选择这种产品而不选择竞争性产品的概率。
下面哪项如果正确，最能支持以上得出的结论

A．可以同时提高一种产品的质量和价格而不改变产品的竞争地位。

B．对于消费者人群中特定的部分来讲，一些产品系列价格较高的品牌比低价品牌更受青睐。

C．竞争性的产品常常试图吸引消费者人群中的不同部分。

D．消费者对一种产品质量的了解来自于这种产品的实际质量。

在产品成本预算中，产品成本总预算金额是将直接材料、直接人工、制造费用以及销售与管理费用的预算金额汇总相加而得到的。

对干部离任时实行自然资源资产审计，对造成生态环境生态损害的要追究责任，对干部离任审计仅限于干部离任时的生态环境状况。

业主对工程项目管理的目的不包括______。

A．实现对工程项目的全面管理
B．实现投资主体的投资目标和期望
C．将工程项目投资控制在预定或可接受的范围之内
D．保证工程项目建成后在项目功能和质量上达到设计标准