.Everyone knows that _______ is dangerous to play with fire, but _______ is difficult is to prevent children from playing with fire.
Because the shop _______, all the T-shirts are sold at half price.
—I’m sorry,but there’s no smoking on this flight.—Oh,I _______ that.Sorry, I won’t again.
—Why did you leave that position?—I _______ a better position at IBM.
—What were you doing when Tony phoned you?—I had just finished my work and _______ to take a shower.
—You learned to drive a car quite young, didn’t you?—Yes, my father _______ me when I was thirteen.