砂芯有哪些功用？
参考答案：
砂芯的功用是形成铸件的内腔、孔洞和铸件外形不能出砂的部位。砂芯局部要求特殊性能的的部分，有时也用砂芯。
If you want to____, you must learn to work hard while you are still young.
A. make your way B. make its way C. make a way Dmake the way
细菌性痢疾
