I yelped and craned my head backward, trying to see what was going on.
我疼得直喊，努力把头转过去，试图看到背上到底怎么了。
An owl's head, for example, can twist so far round that it faces backward, but when the bird wants to look forward again, it must turn its head back the way it came.
比如说猫头鹰可以将正脸一直转到后脑勺的位置，但是如果它再想看到正前方的东西，那整个头部只能原路返回了。
Valves in the veins prevent blood from flowing backward toward the head, but if the valves don't close sufficiently, blood could seep back upward.
静脉中的瓣膜阻止血液倒流到脑部，但是如果瓣膜不足，血液会就会再次流到大脑。
Hermione shuddered and took a step backward. Harry shook his head.
赫敏打了个激灵，朝后退了一步。哈利摇了摇头。
Inhale and raise the arms upward. Slowly bend backward, stretching arms above the head.
吸气，手臂上举，身体舒缓地向后弯曲，伸展手臂。
The trimming head is bent backward for easy reach and maximum control.
在修整头部向后弯曲，方便范围和最大程度地控制。
Roll head gently from side to side, then forward and backward.
柔和地向两边拉伸脖子，然后同样向前低头向后仰脖。
CR-Finishing Film is automatically rewinded. Two groups of ballscrew linear guideway are equipped for the forward and backward movement of polishing head.
抛光砂纸带自动收卷，抛头进、退采用滚珠直线导轨两层工作平台。
Working table fixed, backward moving of double wheel head overall arrangement is used.
采用工作台固定、双砂轮架后移动式布局。
Neck exercise: cross ten fingers and put two hands back of head, backward the head against the hands and neck, then forward close the elbows, two palms press down;
劲部运动：十指交叉抱头于脑后，头上抬与劲部争力，然后向前合肘，下颌内收，两掌向下按；
Neck exercise: cross ten fingers and put two hands back of head, backward the head against the hands and neck, then forward close the elbows, two palms press down;
劲部运动：十指交叉抱头于脑后，头上抬与劲部争力，然后向前合肘，下颌内收，两掌向下按；
应用推荐