when you ........ your hands, teeth, etc., or when they ....., you press them together tightly, usually showing that you are angry, determined or upset

obtained or experienced yourself (adj)

if your stomach .............., it makes a noise, especially because you are hungry

to shake slightly because you are cold

to move your head or body downwards to avoid being hit or seen

to shake  because of a strong feeling

extremely frightening but often exciting

to push somebody gently, especially with your elbow, in order to get their attention

to keep moving your body, your hands or your feet because you are nervous, bored, excited, etc.

a ......... book has been read many times

in which the front part of one vehicle hits the front part of another vehicle

extremely frightening

to lower your body close to the ground by  bending  your  knees  completely