¡¡¡¡Ò»£® Form nouns by adding suffixes to the following:
¡¡¡¡1.pollute 2.explain 3.divide 4.build 5. require
¡¡¡¡6.grow 7.destroy 8.important 9.excite 10.direct
¡¡¡¡11. necessary 12.strong 13.realize 14.arrange 15.survive
¡¡¡¡16.vary 17.depend 18.electric 19.settle 20.difficult