估算方程x2-5=0的根约是______.

题型:填空题

问题:

估算方程x2-5=0的根约是______.

考点:一元二次方程的解法
题型:填空题
已知|
a
|=3
,|
b
|=2,
a
b
的夹角为60°,如果(3
a
+5
b
)⊥(m
a
-
b
),则m的值为(  )
A.
32
23
B.
23
42
C.
29
42
D.
42
32
题型:填空题

如图是我市街道边新设的垃圾分类示意图,空矿泉水瓶应放入哪个垃圾箱中(  )

A.①

B.②

C.③

D.以上都不是

题型:填空题

为了测定某种石灰石中碳酸钙的质量分数,取5g石灰石样品放入烧杯中,将60g稀盐酸分成四次加入烧杯中,充分反应后,测得实验数据如下表(样品中的杂质不与盐酸反应也不溶于水)

次 数第一次第二次第三次第四次
加入稀盐酸质量/g15151515
烧杯内剩余物质量/g19.3433.6848.2463.24
请你分析并进行有关计算:

(1)哪几次反应后,盐酸有剩余______.

(2)石灰石样品中碳酸钙的质量分数.

(3)上述实验结束后,向烧杯内的物质中加入石灰石至不再产生气泡,过滤.求滤液中溶质的质量分数.(结果精确到0.1%)

题型:填空题

I got a job teaching special education at a school in Coachella, California, a desert town about 170 miles from home. It was no (1) job. Street gangs (2) around the school after dark.

"Be careful, " Dad warned me during one of my frequent weekend (3) home. He was concerned about my living (4) , but I needed to be on my own.

One evening, I stayed after school to rearrange my classroom. (5) , I turned out the light and closed the door. Then I (6) toward the gate. It was (7) ! I looked around. Everyone had gone home.

After (8) all the exits, I found just enough (9) to squeeze under a gate in the back of the school. Then I walked toward my car, parked in a field behind the building.Suddenly I heard voices. I (10) around and saw at least eight boys following me. (11) my pace, I reached into my shoulder bag to get my key. I (12) all over the inside of my handbag. But the key wasn’t (13) ! Dear Lord, please help me, I prayed (14) . Suddenly, my fingers touched a loose key in my purse. I didn’t even know if it was for my car, but I took it out and (15) it. It worked!I opened the door, slid in and locked it—just (16) the teenagers surrounded the car. Trembling , I started the engine and (17) away. When I returned to my apartment, the phone was ringing. It was my Dad. I didn’t tell him about my experience; I didn’t want to (18) him. "Oh, I forgot to tell you!" He said, "I had a (n) (19) car key made and slipped it into your purse—just (20) you ever need it.

5()

A.Tired 

B.Finished 

C.Frightened 

D.Hungry

题型:填空题

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