其次，本文要解决的第二个问题就是如何提高壳法用覆膜砂的抗拉强度。
Secondly, another problem that will be solved in this paper is how to improve the intensity of resin coated sand used for shell process.
其次，本文要解决的第二个问题就是如何提高壳法用覆膜砂的抗拉强度。
Secondly, another problem that will be solved in this paper is how to improve the intensity of resin coated sand used for shell process.
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