16.Mr Russel is a good teacher, but he often gives ____ lectures.
A. excellent B. extensive C. sound D. tedious
<tedious>
tedious 很郁悶的、很惹人煩的、單調乏味的
</tedious>
<excellent>
excellent 優秀的、很好的
out-standing 最優秀、杰出的
</excellent>
<extensive>
extensive 廣泛的、廣大的
</extensive>
<sound>
sound n.聲音、adj.非常好的、健全的
</sound>