Thestudentsputupsomesigns________theriverside________thewaterclean.[ ]A.by,tokeepB.at,tokeepC.by,kee

题目简介

Thestudentsputupsomesigns________theriverside________thewaterclean.[ ]A.by,tokeepB.at,tokeepC.by,kee

题目详情

The students put up some signs ________ the riverside ________ the water clean.        
[     ]
A. by, to keep 
B. at, to keep    
C. by, keep   
D. in, for 
题型:单选题难度:中档来源:同步题

答案

A

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