产后大出血引起的希恩综合征最早出现的症状是（）
A.无乳汁分泌
B.神志不清
C.记忆减退
D.怕冷、便秘
E.毛发减少
参考答案：A
下列哪种材料不能用作桥体的龈端
A．陶瓷
B．合金
C．复合树脂
D．热凝塑料
E．自凝塑料
Simon is very regretful. If he had been more careful, he _____ such a big mistake.
A．hasn’t made
B．hadn’t made
C．won’t have made
D．wouldn’t have made
