当声波穿过两种材料的界面时会发生折射,这是由于什么不同?( ) A.声阻抗 B.声

题型:单项选择题

问题:

当声波穿过两种材料的界面时会发生折射,这是由于什么不同?( )

A.声阻抗

B.声速

C.密度

D.探头频率

E.与上述各项无关

考点:大型设备上岗证考试彩色多普勒(CDFI)上岗考试CDFI上岗证考试
题型:单项选择题

A smart phone is a mobile phone built on a mobile operating system, with more advanced computing abilities than a common phone. The first smart phones enabled the users to send and receive emails. Later models added the function of portable media players, pocket video cameras, and GPS navigation units to form one multi-use device. Many modem smart phones also include touchscreens and web browsers that display web pages.

A recent report says we spend an average of two hours and 40 minutes each day looking at a smart phone. That doesn’t mean making calls, but playing phone games and browsing the Web.

Nowadays we always find people checking emails in a restaurant, taking a picture of the food when it arrives, or checking a message during a conversation instead of traditional communication. It’s no secret that our lives are being affected by our smart phones obsession.

However, this phenomenon has never been presented so vividly as in the short YouTube film I Forgot My Phone. Despite only being online for a few days, it's already been viewed more than 10.5 million times. Whether it will be screened in the cinema remains to be seen.

Ironically, YouTube’s data show that the site gets a billion views per day from mobile devices, so a lot of those people watched it on their phones.

The short film, written by and starring actress Charlene Deguzman, shows groups of people in various social situations, the majority of whom are absorbed in their phones instead of the world around them. To a certain extent, we all do it.

小题1:People prefer a smart phone to a common one, because the latter only can help us ______.

A.check emails

B.send messages

C.find the destination

D.watch a video小题2:The underlined word “obsession” in the third paragraph most probably means “______”.

A.devotion

B.contribution

C.addiction

D.emotion小题3:Which of the following is right?

A.People spend as average of two hours and 40 minutes each day using smart phones.

B.The film hasn’t been put on in the cinema.

C.The film is written by an actor named Charlene Deguzman.

D.The film has already been viewed more than 105 million times in the first few days.小题4:When the writer mentions the number of people watching the film from mobile devices in the fifth paragraph, he mainly feels ______.

A.encouraged

B.depressed

C.proud

D.satisfied

题型:单项选择题

群众工作是公安专业工作的有机组成部分,群众工作的情况如何,直接反映在公安专业工作的质量上,公安民警要善于面对面地做好群众工作,掌握做好群众工作的基本功。( )

题型:单项选择题

24岁,G1P0,孕30周, * * 流血3天,增多2小时,急诊入院,查血压90/60mmHg,脉率112次/分,宫底剑突下三横指,臀先露,LSA,胎心136次/分,有规则宫缩。为进一步确诊,首选下列哪项检查()

A.肛查

B. * * 检查

C.B型超声检查

D.颈管内指诊

E.腹部平片

题型:单项选择题

提插补泻法中,补法的操作手法是()

A.轻插重提,幅度小,频率快

B.轻插重提,幅度小,频率慢

C.重插轻提,幅度大,频率快

D.重插轻提,幅度小,频率快

E.重插轻提,幅度小,频率慢

题型:单项选择题

擅自收购烟叶应如何处罚?

更多题库