a)如何指出當前研究的不足以及有目的地引導出自己的研究的重要性
通常在敍述了前人成果之後，用However來引導不足，比如
However, little information..
little attention...
little work...
little data
little research
or few studies
few investigations...
few researchers...
few attempts...
or no
none of these studies
has (have) been less
done on ...
focused on
attempted to
conducted
investigated
studied
(with respect to)
Previous research (studies, records) has (have)
failed to consider
ignored
misinterpreted
neglected to
overestimated, underestimated
misleaded
thus, these previus results are
inconclisive, misleading, unsatisfactory, questionable, controversial..