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【多选题】
在下列哪些条件下，甲烷与氯气能进行卤代反应A.
甲烷与氯气的混合物在室温下，放置在黑暗处
B.
氯气先用光照射，然后在黑暗处迅速地与甲烷混合
C.
在黑暗处，将甲烷与氯气的混合物加热到250℃以上
D.
氯气与甲烷混合后光照
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【多选题】Which two statements are true about analog to digital conversion of voice signals for use in digital telephony networks？ （）
A.
The three required steps in the analog to digital conversion are sampling， encoding， and compression.
B.
The three required steps in the analog to digital conversion are sampling， quantization， and compression.
C.
The three required steps in the analog to digital conversion are sampling， quantization， and encoding.
D.
The output of the sampling process is a pulse code modulation （PCM） signal.
E.
The output of the sampling process is a pulse amplitude modulation （PAM） signal.
【单选题】________ or voice-input devices accept spoken words through a microphone and change the sounds into computer readable signals.
A.
Speech-recognition
B.
Sensor
C.
Sanner
D.
Printer
【单选题】— Why do you drink so much tea? — Well, _____ it doesn't keep me awake in the nights. [ ]
A.
although
B.
as soon as
C.
as long as
D.
while
【单选题】Distress signals may be（）.
A.
red flares
B.
smoke signals
C.
sound signals
D.
Any of the above
【单选题】Why do the middle-aged people prefer tea according to the author?
A.
They become practical and want to save money.
B.
They like the faint and lingering fragrance of the Chinese tea.
C.
Coffee is too bitter for them to drink.
D.
Hot tea is good for their health.
【单选题】Christmas is traditionally an important religious festival in many Western countries, but it’s also celebrated in China. Why do you celebrate Christmas?
A.
Because it’s an opportunity to go shopping and join in an international celebration.
B.
Out of respect for other people’s religions and religious festivals.
C.
Due to its religious importance to me.
D.
Because my friends and classmates all celebrate Christmas.
【单选题】Why is the tea set important?
A.
A good tea set can reflect the color, aroma and taste of tea.
B.
While enjoying tea, it is also helpful to appreciate the fine tea set.
C.
Tea sets are the father of tea.
D.
All of the above.
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