搜题请搜索小程序“爱下问搜题”
问题 填空题

点火提前角过小（即点火过迟），则混合气一面燃烧，活塞一面（），燃烧过程是在气缸容积不断（）的情况下进行，使炽热的气体与气缸壁接触面积（），气体最高压力（），致使发动机功率（），油耗（）。

答案

参考答案：下行；增大；增大；降低；下降；上升

完形填空

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.

查看答案
单项选择题

在PR1592小型配料控制器的物料表中设置的：能决定本次配料的起点的参数是（）

A、细称值

B、过冲量

C、精度范围

D、无流量

E、配料方式

F、最小水准脱离时间
查看答案