Dadfrom his paper and smiled when I entered the living room.
A. looked afer
B. looked down
C. looked for
D. looked up
查看答案
My sisiter stopped the car because she saw someone his hand with his thumb raised.
A. putting away
B. putting off
C. putting out
D. putting on
These dishes are cold. You shouldif you want to eat them.
A. heat them up
B. heat up it
C. heat it up
D. heat up them
MCS-51单片机的( )口作为输出应用时必须外接上拉电阻。
A. P0
B. P1
C. P2
D. P3
当8051单片机采用12MHz振荡频率,其1个机器周期为( )μs。
A. 0.5
B. 1
C. 2
D. 4