Everyone knows that________ is dangerous to play with fire, but________ is difficult is to prevent children from playing with fire.
._________breaks the law should be punished .
Mabel insisted that she_________someone in the next room just now .
Tom is very confident_________ Mary is shy and quiet .
.--- Merry Christmas ! --- _________.
To go to bed early and to get up early_________good_________one’s health .