以下材料是20世纪下半叶我国强沙尘暴发生频率与土地沙化速度统计表，据此回答1~2题
1、表中显示我国的土地沙化速度不断加快，其原因可能是[ ]
A、我国气候有变冷的趋势
B、全球气温上升，地面植被死亡所致
C、长江中下游地区毁林现象严重
D、西北干旱地区生态环境进一步恶化
2、为了制止强沙尘暴次数增多和沙化速度加快的趋势，应采取的积极有效的措施是[ ]
A、开采地下水灌溉，变沙地为耕地和草地
B、在干旱地区减少耕地，扩大牧场，发展畜牧业
C、采取合理办法调整当地产业结构，以减轻生态环境的压力
D、禁止干旱地区任何经济活动的开展，以保护当地脆弱的生态环境
1、D
2、C
长途运输鱼苗时，常在水中加入少量过氧化钙（CaO2）固体．甲、乙两位同学发现往水中投入过氧化钙时产生气泡．
提出问题：当把过氧化钙投入足量水中时，最终生成什么物质？
进行猜想：甲同学：生成氧化钙和氧气；乙同学：生成氢氧化钙和氧气．
（1）同学和老师都认为______同学的猜想是错误的，其理由是______．
（2）请设计一个实验方案来验证过氧化钙和水反应产生的另一种物质是氢氧化钙：
| 实验步骤及操作方法 | 预期的实验现象 | 结论 |
| ①取少量过氧化钙放入试管中，加足量水，振荡， ②______． | ①产生气泡． ②______． | 过氧化钙和水反应产生的另一种物质是氢氧化钙 |
（4）过氧化钙和水反应的化学方程式为______．
| At the public radio station KEXP in Seattle, there’s a simple procedure for evaluating new technology. "We just go ahead and do stuff," says one of the station’s morning disc jockeys. That’s how the quirky station created one of the first music podcasts—without support from major record companies. A podcast is a digital recording of a radio-style audio program that can be downloaded from the Internet and played on a digital music player. Many podcasters think the technology could revolutionize radio as TiVo did television. Podcasting is a great way for KEXP to reach thousands of new listeners, especially those outside of Seattle. But the station can’t podcast programs such as John in the morning—a variety of independent and mainstream music—because record companies haven’t provided an easy, affordable way for podcasters to license songs. That’s why most podcasts today are talk radio. KEXP decided that it couldn’t sit around and wait and wait for a major label to sign off on this. So it invited 14 unsigned or small bands from the Seattle area to contribute songs to a podcast. The station asked a lawyer—a listener who volunteers at the station—to draw up a simple contract for the bands. KEXP did not release numbers but said the podcast was a hit. KEXP is now podcasting some live performances to which it owns the rights. Since podcasts are recordings, they can be played at any time. Listeners can pause, fast-forward or rewind them. And since podcasts are posted online, listeners can download programs from radio stations and independent broadcasters from all over the world. The podcasts can also be hacked and pirated. An enterprising listener could pull songs out of a podcast and turn them into music files or CDs. That’s why many record companies say the technology is promising but problematic. But record labels worry that listeners will pirate the songs contained in the downloaded radio shows. For example, OK Go and several other emerging bands with EMI have their own podcasts. But EMI is not ready to approve a blanket podcasting license. "Podcasting is potentially very exciting," says Executive Vice-president Adam Klein. The result: yet another Napster-like standoff over piracy and music rights. |
Where the words "without support from major record companies" are, the context reads that music broadcast programs ______ record companies.
A．must have the support of
B．require the participation of
C．may enlist the assistance of
D．should enter partnership with