10. None of the servants was ______ when Mr Smith wanted to send a message.
A. available B. approachable C. attainable D. applicable
<available>
available 可获得的，有用的
</available>
<approachable>
approachable 可接近的
</approachable>
<attainable>
attainable 可获得的
</attainable>
<applicable>
applicable 可应用的
</applicable>
