ril 10, 2010 air crash, with a Russian Tu-145 plane _______ Poland’s president Lech Kaczinsky, his wife and many Polish government and militaryofficials, shocked the whole world.

Meyer and his team were the first ______ how the disease spreads fromanimals to humans.

50. Teachers should be _____ with their students but should not be _____ on them.

She is making herself ill with _____ overher son’s future.

You had better go at once, ____ you?