用对热敏感的元件来探测火灾的发生的探测器是（）A、感烟式探测_爱下问搜题

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问题单项选择题

用对热敏感的元件来探测火灾的发生的探测器是（）

A、感烟式探测器

B、感温式探测器

C、光式探测器

D、可燃气体探测器

答案

参考答案：B

完形填空

完形填空。

       Mr.  Smith  is  a  good  teacher.  He  teaches  English  very  well .  He  is  1 to  his  students,  so
they  like  him  a  lot. There  are (有) fifty  students  in  2 class.  Mr.  Smith   always  3 English   in
class.  He  and   his  students  are  4 friends,  too.  Now  some  of  the  students  5 on  the  playground.
Bill  and  Mike  6 . Tom  and  John  are  jumping.  Mary  and  Lucy  are  7 a  kite. Are  Lily  and  Maria
flying  a  kite, 8 ?  No,  they are playing 9 .  What's  Mr.  Smith  doing?  Look!  He is  also  playing
10   them.  How happy they are !

( )1. A. friendly
( )2. A. their
( )3. A. talk
( )4. A. nice
( )5. A. are  playing
( )6. A. are  running
( )7. A. playing
( )8. A. also
( )9. A. the  football
( )10. A. and

B. interesting
B. his
B. say
B. fine
B. play
B. run
B. flying
B. or
B. a  football
B. with

C. beautiful
C. her
C. speaks
C. new
C. plays
C. running
C. doing
C. too
C. the  game
C. for

D. happy
D. its
D. speak
D. good
D. is playing
D. not run
D. sitting
D. and
D. games
D. to

问答题

1919年卢瑟福通过如图所示的实验装置，第一次完成了原子核的人工转变，并由此发现______．图中银箔的作用是______．完成该实验的下列核反应方程：₂⁴He+₇¹⁴N→₈¹⁷O+______．