1、
Falling behind in math class, I found it difficult to keep up with my peers.
在数学课上落后，我发现很难跟上同学们的进度。
金山词霸
2、
The company agreed to keep up production to compensate for the lost supply.
这家公司同意保持生产以弥补丢失的供货。
金山词霸
3、
To keep the enemy out his empire, Qin Shihuang had all the walls joined up.
为了御敌于国门之外, 秦始皇把所有的城墙连接起来.
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