问题 选择题

下列有关物质分类的说法中正确的是(  )

A.由同种元素组成的物质一定是纯净物

B.由同种元素组成的物质叫单质

C.只含一种元素的物质一定不是混合物

D.氧化物一定是化合物

答案

A、纯净物的概念是由一种物质组成的叫纯净物,而不是一种元素组成的;例如:由氧气和臭氧组成的混合物虽然只由一种元素氧元素,但属于混合物;故错

B、由氧气和臭氧组成的混合物虽然只由一种元素组成,但不属于单质.故错;

C、含有一种元素的物质可能是混合物,例如:金刚石和石墨的混合形成的是混合物其中含有一种元素碳元素;故错

D、化合物中包含氧化物;故对

故选D

完形填空

“Everything happens for the best,” my grandmother said whenever things weren’t going my way. “Don’t worry, one day your luck (1) _____________(change). ”

Grandmother was right, as I discovered after graduating from college. I had decided to be sports announcer (广播员) in a radio station, so I (2) _____________ ( go) to Shanghai and knocked on the door of every station. But I got refused every time.

In one station, a kind lady said my problem was short of experience. “ Get some work with a small station and (3)_______________(work) your way up ,” she said.

I couldn’t get a job there, either. Then my dad told me a businessman had opened a company and needed someone (4 )_____________ ( manage) the sports center. But again, I didn’t get the job.

I felt really down. “Your luck will change,” Granny reminded me. I tried another radio station in Beijing. But the owner, a nice man, told me he already had someone.

As I left his office, I asked, “ How can someone be a sports announcer if he ( 5 )_____________(not, get) a job in a radio station?”

I ()______________( wait) for the elevator when I heard the man call, “What was that you said about sports? Do you know anything about football?” I (7)______________(put) in front of a microphone and asked to imagine I was commenting (评论) on a football game. “Now you (8)____________ (watch) the football game between Lu Neng and Shen Hua. . . ”

On my way home, Granny’s words came back to me, “One day your luck will change, boy. And when it (9 ) ____________( happen) , it’ll feel twice as good because of all the disappointment (失望) you (10) ____________ ( have) . ” At that moment I knew just what she meant.

判断题