胰腺囊肿和实质性肿块最好的超声鉴别方法是
A．M型超声
B．B型超声
C．A型超声
D．彩色多普勒
E．超声造影
参考答案：D
Only when you have finished your homework _____ go home. [ ]
A. can you
B. would you
C. you will
D. you can
齿轮传动装配时，齿侧间隙过大时会产生冲击，侧隙过小时，传动会不灵活，甚至卡齿。
