— Are they pencils? — No, __________.[ ]
A. they are
B. they aren't
C. they not
答案:B
除()外,大多数土壤中裸钢腐蚀的主要形式是氧浓差电池。
A.碱性土壤
B.酸性土壤
C.中性土壤
D.盐碱土
具有同质多晶型
A.可可豆脂B.泊洛沙姆C.甘油明胶D.聚乙二醇E.羊毛脂