The introduction of CELS to the English training market in China is only a result of their efforts.

CELS 英语技能证书在中国市场上的隆重推出，就是其所作的此种努力之一。

Cels are more of a problem because they are more expensive to retake and take more time to produce.

赛璐璐胶片是个更大的问题，因为重做这东西更贵，也更花时间。