当8051单片机的晶振频率为12MHZ时,ALE地址锁存信号端的输出频率为2MHZ的方脉冲。
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you pay in advance, we won' t charge you for delivery.
As long as
B. As though
C. In order that
D. even though
Once customers come to rely ___ these systems, they almost never take their business elsewehere.
A. on
B. at
C. of
D. by
Detailed preparation must be ____ before your sign a contract.
A. talked
B. looked
C. carried
D. done
As your business grows, you may need (employ)___ workers with different skilss.