一单能X射线通过3个半值层的厚度后强度为原来的() A.1/2 B.1/3 C.1/

题型:单项选择题 A1/A2型题

问题:

一单能X射线通过3个半值层的厚度后强度为原来的()

A.1/2

B.1/3

C.1/4

D.1/8

E.1/16

考点:放射医学技术(士)X线物理与防护X线物理与防护题库
题型:单项选择题 A1/A2型题

In China, parents often tell their kids not to waste food. However, it's reported that a lot of food is wasted in restaurants every day.

Many people say when they eat out, they usually order a lot of dishes and they can't eat them up. One person in Chengdu, Sichuan Province says he takes away the leftovers. "Usually we'll have some leftovers after meals, because when I invite friends to eat out, I don't know how much they can eat, so I order lots of dishes to make sure everybody has enough food."

While another person in Fuzhou, Fujian Province says she never packs what is left on the dining table. "What I usually experience during eating out is a big meal. I seldom take away the leftovers because we often have other activities after the meals, and it's not convenient to take the leftovers. And when no one suggests taking away leftovers, I won't do so."

Some people say they only take away leftovers when they eat out with family, but not if they eat with friends or colleagues (同事).

Food waste means washing money as well as wasting precious resources (宝贵资源). When food is thrown away, it becomes rubbish and can be harmful to the environment.

We should realize how important it is to save food. It's wise to order proper food for our meals. If there're leftovers, it's better to take home. To save food, we should start with ourselves and start from now.

小题1:_________food is wasted in the restaurants of our country every day.

A.Little

B.Many

C.Few

D.Much小题2:The underlined word "leftovers" means________ in Chinese.

A.残留物

B.离开

C.剩菜

D.垃圾小题3:Which of the following is not mentioned?

A.They wan to give the leftovers to the servers.

B.The person never packs what is left on the dining table.

C.The leftovers can be harm to the environment.

D.Some people only take away leftovers when they eat out with family小题4:From the passage, it's necessary for us to________ when we eat out.

A.pack our favorite food

B.invite our friend for dinner

C.throw the leftovers away

D.order proper food for our meal and finish all on our plates小题5:The best tile of this passage is__________

A.Washing Money

B.Saving Food

C.Throwing Away Leftovers

D.Saving Money

题型:单项选择题 A1/A2型题

在一个淡水生态系统中,食物链是微小生物→剑水藻→蜻蜓幼鱼→小鱼→大鱼,当这个生态系统被排放了难以分解的有毒物质时,体内有毒物质含量是 [ ]

A.微小水生植物最多

B.大鱼最多

C.各种生物一样多

D.活的时间比较长的

题型:单项选择题 A1/A2型题

经纪类证券公司可经营证券经纪业务、证券自营义务、证券承销业务等。

题型:单项选择题 A1/A2型题

对称三相交流电路无功功率的表达式sin3UIQ中的电压和电流是()。

A、线电压和线电流

B、线电压和相电流

C、相电压和线电流

D、相电压和相电流

题型:单项选择题 A1/A2型题

简述GPS系统的特点。

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