I usually have breakfast ____________ 8: 00.[ ]
A. in
B. at
C. on
答案：B
Science and technology is changing fast nowadays. I bought this MP3 player at the beginning of this year but now it's out of ________.
A．date
B．order
C．use
D．sight
看火孔的压力应为（）。
A．0-5Pa
B．5-10Pa
C．10Pa
D．20Pa
