胃静脉曲张常发生的部位是()
A.体部
B.胃底部
C.贲门部
D.胃窦部
E.幽门部
参考答案:B, C
The teacher assigned the task to the three boys and ________ did his share.
A.any
B.all
C.every
D.each
道口闪光器的闪光频率为90-120次/min。