1.（★★★★★）Jumping out of airplane at ten thousand feet is quite________exciting experience.
A.不填；the B.不填；an C.an；an D.the；the
2.（★★★★★）Many people agree that________knowledge of English is________must in international trade today.
A.a；a B.the；an C.the；the D.不填；the
3.（★★★★★）One way to understand thousands of new words is to gain________good knowledge of basic word information.
A./ B.the C.a D.one
