Some of the perceived candidates' weaknesses can be summarized as follows:
(1) poor knowledge of the subject-matter;
(2) misinterpretation of questions;
(3) failure to expatiate on points made;
(4) disobedience to rubrics, etc.
Candidates can overcome these shortcomings if the following precautionary measures are taken:
qualified teachers should be employed by schools to teach the subject. candidates should endeavour to devote the first few minutes of  their time to read the instructions on question papers.
candidates should endeavour to expatiate their points.
candidates should improve on the usage of English language.