第7题: [单项选择]腹外疝最重要的致病因素是 A. 慢性便秘 B. 慢性咳嗽 C. 妊娠 D. 婴儿经常啼哭 E. 腹壁强度降低 参考答案:E 答案解析:腹外疝形成原因包括腹壁强度降低及腹内压力增高两方面,前者为根本因素,后者为诱发因素。慢性便秘、慢性咳嗽、妊娠、婴儿经常啼哭均为引起腹内压增高的因素,属于诱因。
A. To practice speaking slowly. B. To record a voice from the television. C. To play a speech by the professor. D. To evaluate their own voices. 参考答案:D