You have been the auditor of a construction company, Antler Ltd (Antler), for the past four years. Using Antler's pre-audit trial balance, you have calculated profitability ratios for year 2021. You also have the values for the previous two years as follows:

	2021 (unaudited figures)	2020 (audited figures)	2019 (audited figures)
Gross profit margin	0.36	0.26	0.31
Profit margin	0.09	0.14	0.17

You are a little confused because the profit margin shows declining profitability, but the gross profit margin has improved this year. The gross profit margin is also higher in 2021 than in the previous two years.

Required:

1. List FOUR possible reasons for the pattern observed in the gross profit and profit margins.

For each possible reason identified in (a) above, list the account(s) and/or transactions that would need special attention in the audit.