若a＞b，c∈R，则在下列结论中成立的是（） A．ac＞bc B．a-c＞b-cC_爱下问搜题

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问题选择题

若a＞b，c∈R，则在下列结论中成立的是（　　）

A．ac＞bc

B．a-c＞b-c

C．a²＞b²

D．

1

a

＜

1

b

答案

∵a＞b，c∈R，

∴令c=0，则ac=bc=0，可排除A；

再令a=0，c=-2，则0＜4，可排除C；

再令a=1，b=-1，则

1

1

＞

1

-1

，可排除D；

若a＞b则a-c＞b-c，正确．

故选B．

判断题

我国四大发明中的火药是唐朝时期出现的。

完形填空

When I was a teenager I volunteered to work at the water station at a 10,000m race. My job was to   34   water to the runners. I remember being so 35   to see all the different kinds of people who passed by and grabbed a cup of water. Some ran past, some walked past and a few wheeled past. I saw so many types of people doing it. I thought maybe I could do it too! So the next year I 36 up for the race.
That first 10,000m race was quite an experience. I jogged, I walked, I jogged and I walked 37 , I didn’t know if I could finish. Then came a defining (决定性) 38 .
At one point near the end, a 70-year-old man ran past me, very, very fast, and I felt 39 because I was 50 years younger than he but I couldn’t even keep up with him. I felt 40 for a second.
But then I realized something. He was running his race and I was running mine. He had 41   abilities, experience, training and goals for himself. I had mine. Remember my 42 was only to finish.
After a minute, it 43 me that this was a lesson I could draw from. I learned something about myself in that moment. I turned my embarrassment into 44   .
I decided that I would not give up on running races. In fact, I would run even more races and I would learn how to train and prepare 45 and one day I would be one of those 70-year-old persons who were still running. As I crossed the finish line, I was proud of my accomplishment. In life we all have those moments where we 46 ourselves to others. It’s only natural . Don’t allow those moments to 47 you. Turn them into motivation and let them inspire you. With the proper preparation and training, you can improve your result to 48 anything you want in life.

A．embarrassed

C．inspiration

D．expectation