螺栓联接的防松方法有哪些?
参考答案:
(1)双螺母;
(2)弹簧垫圈防松;
(3)自锁螺母;
(4)开口销;
(5)止推垫圈
(6)保险丝防松;
(7)永久防松。
. --- This kind of food is said to contain poisonous chemicals.
--- So why not _____ it?
A.murder
B.arrest
C.boycott
D.abolish
门电路心血池显像心室壁瘤的典型影像特征有()
A.房室峰之间出现异常峰
B.局部心室壁呈反向运动
C.心室相角程明显增宽
D.心室壁影像形态异常,局部膨出
E.炸面图样改变