People __1.___________ (live) in different countries made different kinds of words. Today there are about fifteen hundred __2.________ in the world. Each contains many thousands of words. A very large dictionary, for example, contains four __3.__________ five hundred thousand words. But we do not need __4.________ these. To read short stories you need to know only about two thousand words. __5._________ you leave school, you will learn only one thousand or more.

The words you know are called your vocabulary. You should try to make your vocabulary __6.____________ (big). Read as many books as we can. There are a lot of books __7.___________ (write) in easy English. You will enjoy them. When you come across __8.___________ new word, look it ___9.____________ in your dictionary. Your dictionary is your __10.__________ (much) useful book.

假设A、B为布尔变量，对于逻辑表达式（A＆＆B‖C），需要（）个测试用例才能完成判定覆盖（DC）。

A.2

B.3

C.4

D.5