飞机无线电通信系统类型有() A.甚高频通信系统 B.高频通信系统 C.选择呼叫系统

题型:多项选择题

问题:

飞机无线电通信系统类型有()

A.甚高频通信系统

B.高频通信系统

C.选择呼叫系统

D.音频综合系统

考点:民用航空器维修执照考试飞机结构修理综合练习飞机结构修理综合练习题库
题型:多项选择题

当球磨机的转速率在76?8%范围内时,随转速率增加磨机充填率也随之变化,其值()。

题型:多项选择题

汽车行驶中经常变速。为此,小玲同学设想了一种自动控制装置,通过车尾红灯警示随后车辆,原理如图:弹簧一端固定,另一端连在质量较大的绝缘滑块上,金属片与触点构成开关。图为车子静止或匀速直线运动时的状态,则当汽车在_____________(填“启动或加速”、“刹车或减速”)时,由于滑块具有_______________,会使尾灯亮起。

题型:多项选择题
如图所示,矩形线圈有N匝,长为a,宽为b,每匝线圈电阻为R,从磁感应强度为B的匀强磁场中以速度v匀速拉出来,那么,产生的感应电动势和流经线圈中的感应电流的大小应为(  )

A.E=Bav,

B.E=NBav,

C.E=Bav,

D.E=NBav,

题型:多项选择题

阅读理解。

     Our "Mommy and Me" time began two years ago. My next-door neighbor and fellow mother, Christie,

and I were out in our front yards, watching seven children of age 6 and under ride their bikes up and down.

"I wish I could take one of my children out alone," said Christie.

     Then we worked out a plan: When Christie takes one of her children out, I'll watch her other three. And

when she watches two of mine, I'll take someone out.

     The children were extremely quick to accept the idea of "Mommy and Me" time. Christie's daughter,

McKenzie, went first. When she returned, the other children showered her with tons of questions. McKenzie

was smiling broadly. Christie looked refreshed and happy. "She's like a different child when there's no one

else around," Christie shared with me quickly. With her mother all to herself, McKenzie didn't have to make

an effort to gain attention.

     Just as Christie had noticed changes in McKenzie, I also discovered something different in each of my

children during our alone times. For example, I am always surprised when my daughter, who is seldom close

to me, holds my hand frequently. My stuttering (口吃的) son, Tom, doesn't stutter once during our activities

since he doesn't have to struggle for a chance to speak. And the other son, Sam, who's always a follower

when around other children shines as a leader during our times together.

     The "Mommy and Me" time allows us to be simply alone and away with each child-talking, sharing, and

laughing, which has been the biggest gain. Every child deserves (应得到) to be an only child at least once in

a while.

1. What is the text mainly about?

A. The experience of the only child being with mother.

B. The advantage of spending time with one child at a time.

C. The happy life of two families.

D. The basic needs of children.

2. Right after McKenzie came back, the other children were _____.

A. happy

B. curious

C. regretful

D. friendly

3. What is one of the changes the author finds in her children?

A. The daughter acts like a leader.

B. Sam holds her hand more often.

C. The boys become better followers.

D. Tom has less difficulty in speaking.

4. The author seems to believe that _____.

A. having brothers and sisters is fun

B. it's tiring to look after three children

C. every child needs parents' full attention

D. parents should watch others' children

题型:多项选择题

不属于饮用水水质标准中的化学指标是()

A.COD

B.DO

C.BOD

D.pH

E.CCl4

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