she can't be his mother这个句子的反意疑问句应该是什么,是can she还是is she

反义疑问句的口诀：前肯后否,前否后肯,前be后be,前无be后加助,时态一致.
所以she can't be his mother,isn't she?句子中有情态动词can，前面是否定的，后面是肯定的~是不是句子中有be的后面肯定是用be的吗？即使be前面还有情态动词can~纠正：she can't be his mother,is she?（不好意思，疏忽了）句子中有be的后面肯定是用be，be前面有情态动词can时，can在这里一般都表示推测，所以后面的反义疑问也用be.