1.They walked in the dark without saying ______ word and no one was cheerful enough to break ______ silence.
A. a ; /
B. a ; the

2.—— Excuse me, are you going to buy _____ book?
—— Well, I need it for ______ class but it’s too expensive.
A.the ; a
B.the ; the

3. I don’t know who invented _______ telephone , but it’s really ______ most wonderful invention .
A. the ; a
B. / ; a

1:say a word ;根据整个句意翻译:没有说一句话.word是可数名词.
break the silence 打破沉寂 这里用"the"表特指.
选B

2:根据提问人语气,他已经知道回答者要买的那本书.所以这里用"the"表特指.
第二个空:我需要它一节课,但是它太贵了.(表明回答者觉得不值)
这里我认为用"a"修饰.
选A


3:我不知道谁发明了电话.这里应用"the"表特指.
但这是一项极好的发明."一项",用"a"修饰invention.
选A

错了请告诉我....谢谢