( 1 ) 毒药，有毒，毒死
1. Not all snakes are __________.
2. We can sometimes be __________ by bad food.
3. Hate is a __________ for which there is no antidote(解毒药).
( 2 ) 有礼貌，有教养
1. Bob __________ stood aside and let the lady go through the doorway first.
2. The children from that school are known for their __________.
3. It is __________ to say "Thank you" and to open doors for people.
( 3 ) 政治，政治的
1. He left his own country for __________ reasons.
2. "__________ is much more difficult than physics," said Einstein.
( 4 ) 弄脏，污染
1. All those waste products are __________ the rivers.
2. The new law will reduce ____________ of the air.
