安装在空气压缩机输出之后的总风缸上,在空气压力超过规定值时排出过剩的压缩空气,以防损坏空气设备的装置是( )
A.安全阀
B.中继阀
C.电磁阀
某男性患者,被确诊为输尿管结石。突发腹部绞痛,结石可能嵌顿的位置为
A. 肾盂与输尿管移行处
B. 输尿管跨髂血管处
C. 输尿管穿膀胱壁处
D. 尿道内口
E. 以上均有可能
对输尿管的正确描述是
A. 起于肾门
B. 开口于膀胱体的两侧
C. 沿腰大肌后面下行
D. 可分为腹段和盆段两部分
E. 长约20~30厘米
I did not get your letter until yesterday. (Rewrite the sentence, emphasizing the underlined part of a sentence with a cleft sentence(部分强调句).)It was not until that I got your letter.