1. [单选题]扩展名默认为wav的文件属于（） 文件。
A. 声音
B. 压缩
C. 图像
D. 文本
2. [单选题]属于第3层VPN协议。
A. TCP
B. IPsec
C. PPOE
D. SSL
3. [单选题]is NOT a concept of White Box Testing.
A. You should execute all logical decisions on their tree and false sides.
B. You should execute all independent paths within a module at least once.
C. You should execute all loops at their boundary conditions.
D. You should execute all interfaces at their boundary conditions.
