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某项工程,甲、乙两人先合做4天,剩下的工程由甲再单独做5天完成.已知乙单独完成这...
某项工程,甲、乙两人先合做4天,剩下的工程由甲再单独做5天完成.已知乙单独完成这项工程比甲单独完成这项工程少5天.如果设甲单独完成这项工程需x天,那么下列各方程中,正确的是( )
A.
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131022164818765838090/SYS201310221648187658380015_ST/0.png)
-
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131022164818765838090/SYS201310221648187658380015_ST/1.png)
=1
B.
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131022164818765838090/SYS201310221648187658380015_ST/2.png)
+4(
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131022164818765838090/SYS201310221648187658380015_ST/3.png)
+
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131022164818765838090/SYS201310221648187658380015_ST/4.png)
)=1
C.
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131022164818765838090/SYS201310221648187658380015_ST/5.png)
=1-
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131022164818765838090/SYS201310221648187658380015_ST/6.png)
D.
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131022164818765838090/SYS201310221648187658380015_ST/7.png)
+
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131022164818765838090/SYS201310221648187658380015_ST/8.png)
=1
考点分析:
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