17.(A). Henry was startled by the dog’s bark.

　　(B). The dog barked because Henry was jumping.

　　(C). Henry jumped over the dog.

　　(D). The dog barked in spite of Henry’s commands.

　　18.(A). He explained all about the circulatory system.

　　(B). He said the same thing over and over again.

　　(C). What he said persuaded nobody.

　　(D). His explanations were a source of pride.

　　答案与音频文本：

　　AC

　　17. The dog barked and Henry jumped.

　　18. All his explanations were in vain.