Grammar
Pronouns
Vague References
One very common mistake is the use of personal pronouns they and it for very vague references. Here is an example:
They say that prices of HDB flats are rising.
In formal writing, it is important to cite the source of information (c.f. Documentation). Using the construction they say without first clarifying what the pronoun they is referring to serves to confuse your reader and dilute your claims.
