(1)计算:-2-2+|1-1sin45°|×(8+2);(2)解方程:xx-1

题型:解答题

问题:

(1)计算:-2-2+|1-
1
sin45°
|×(
8
+2)

(2)解方程:
x
x-1
-1=
3
x2+x-2
考点:零指数幂(负指数幂和指数为1)解分式方程二次根式的加减乘除混合运算,二次根式的化简特殊角三角函数值
题型:解答题

When I was six, Dad brought home a dog one day, who was called “Brownie”. My brothers and I all loved Brownie and did different things with her. One of us would walk her, another would feed her, then there were baths, playing catch and many other games. Brownie, in return, loved each and every one of us. One thing that most touched my heart was that she would go to whoever was sick and just be with them. We always felt better when she was around.

One day, as I was getting her food, she chewed up(咬破) one of Dad’s shoes, which had to be thrown away in the end. I knew Dad would be mad and I had to let her know what she did was wrong. When I looked at her and said, “Bad girl,” she looked down at the ground and then went and hid. I saw a tear in her eyes.

Brownie turned out to be more than just our family pet. She went everywhere with us. People would stop and ask if they could pet her. Of course she’d let anyone pet her. She was just the most lovable dog. There were many times when we’d be out walking and a small child would come over and pull on her hair. She never barked (咬) or tried to get away. Funny thing is she would smile. This frightened people because they thought she was showing her teeth. Far from the truth, she loved everyone.

Now many years have passed since Brownie died of old age. I still miss the days when she was with us.

Which of the following best describes Brownie?()

A.Shy.

B.Polite.

C.Brave.

D.Caring.

题型:解答题
滑轮组在建筑中应用广泛,如图所示为建筑工人自制的滑轮组,某工人用此滑轮组将重力为800N的重物均匀提高2m,所用的拉力是500N(不计滑轮和绳之间的摩擦).关于滑轮组的说法正确的是(  )

A.滑轮组的机械效率100%

B.工人通过滑轮组所做的有用功1000J

C.若匀速提升1000N重物,需用拉力为600N

D.若匀速提升1000N重物,滑轮组的机械效率80%

题型:解答题

汽车作安全检查时,检验前照灯亮度的单位是()。

A.勒克斯

B.烛光

C.流明

D.坎德拉

题型:解答题

在火药燃烧的特性中,______是标志火药做功能力的参量,一般是指1kg火药燃烧时气体产物所做的功。

A.能量特征
B.燃烧特性
C.力学特性
D.安定性

题型:解答题

关于HBV,下列说法正确的为()

A.抵抗力较强,但煮沸10分钟可灭活

B.RNA病毒

C.消化道传播多见

D.HBV对肝细胞有直接损伤作用

E.HBV-Ab无保护性

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